feat: turn most class variables into instance variables in the Component classes (#5252)

* refactor: improve type checking and initialization in BaseComponent class

- Moved UUID import to TYPE_CHECKING for better type hinting without runtime overhead.
- Reorganized the initialization of class attributes within the __init__ method for clarity and consistency.
- Enhanced the __setattr__ method to handle potential KeyError and AttributeError when checking immutability of _user_id.

* refactor: streamline CustomComponent initialization and enhance attribute management

- Introduced ClassVar constants for better clarity and organization.
- Removed redundant class attributes and restructured instance attribute initialization for improved readability.
- Ensured that instance-specific attributes are initialized before calling the parent class's constructor.
- Enhanced the overall structure of the CustomComponent class to facilitate future maintenance and development.

* refactor: enhance Component initialization and attribute management

- Reorganized the __init__ method to initialize instance-specific attributes before calling the parent class constructor.
- Introduced new instance attributes for better management of inputs, outputs, and internal state.
- Improved clarity by processing input kwargs and ensuring unique ID assignment for components.
- Streamlined the setup process for inputs and outputs, enhancing overall structure and maintainability.

* test: Add unit tests for ChatInput component to verify attribute independence

src/backend/tests/unit/custom/component/test_component_instance_attributes.py

@@ -0,0 +1,118 @@
+import pytest
+from langflow.components.inputs.chat import ChatInput
+from langflow.schema.message import Message
+
+
+@pytest.fixture
+def chat_input_instances():
+    """Create two instances of ChatInput for testing."""
+    chat1 = ChatInput()
+    chat2 = ChatInput()
+    return chat1, chat2
+
+
+def test_input_value_independence(chat_input_instances):
+    """Test that input_value is independent between instances."""
+    chat1, chat2 = chat_input_instances
+
+    # Set different input values
+    chat1.build(input_value="Hello from chat1")
+    chat2.build(input_value="Hello from chat2")
+
+    # Verify values are different
+    assert chat1.input_value != chat2.input_value
+    assert chat1.input_value == "Hello from chat1"
+    assert chat2.input_value == "Hello from chat2"
+
+
+def test_sender_name_independence(chat_input_instances):
+    """Test that sender_name is independent between instances."""
+    chat1, chat2 = chat_input_instances
+
+    # Set different sender names
+    chat1.build(sender_name="Alice")
+    chat2.build(sender_name="Bob")
+
+    # Verify values are different
+    assert chat1.sender_name != chat2.sender_name
+    assert chat1.sender_name == "Alice"
+    assert chat2.sender_name == "Bob"
+
+
+def test_multiple_attributes_independence(chat_input_instances):
+    """Test that multiple attributes are independent between instances."""
+    chat1, chat2 = chat_input_instances
+
+    # Set multiple attributes for chat1
+    chat1.build(input_value="Message 1", sender_name="Alice", background_color="blue", text_color="white")
+
+    # Set different attributes for chat2
+    chat2.build(input_value="Message 2", sender_name="Bob", background_color="red", text_color="black")
+
+    # Verify all attributes are independent
+    assert chat1.input_value != chat2.input_value
+    assert chat1.sender_name != chat2.sender_name
+    assert chat1.background_color != chat2.background_color
+    assert chat1.text_color != chat2.text_color
+
+
+async def test_message_output_independence(chat_input_instances):
+    """Test that message outputs are independent between instances."""
+    chat1, chat2 = chat_input_instances
+
+    # Configure different messages
+    chat1.build(
+        input_value="Hello from chat1",
+        sender_name="Alice",
+        should_store_message=False,  # Prevent actual message storage
+    )
+    chat2.build(
+        input_value="Hello from chat2",
+        sender_name="Bob",
+        should_store_message=False,  # Prevent actual message storage
+    )
+
+    # Get messages from both instances
+    message1 = await chat1.message_response()
+    message2 = await chat2.message_response()
+
+    # Verify messages are different
+    assert isinstance(message1, Message)
+    assert isinstance(message2, Message)
+    assert message1.text != message2.text
+    assert message1.sender_name != message2.sender_name
+
+
+async def test_status_independence(chat_input_instances):
+    """Test that status attribute is independent between instances."""
+    chat1, chat2 = chat_input_instances
+
+    # Configure and run messages
+    chat1.build(input_value="Status test 1", sender_name="Alice", should_store_message=False)
+    chat2.build(input_value="Status test 2", sender_name="Bob", should_store_message=False)
+
+    # Generate messages to update status
+    await chat1.message_response()
+    await chat2.message_response()
+
+    # Verify status values are different
+    assert chat1.status != chat2.status
+    assert chat1.status.text == "Status test 1"
+    assert chat2.status.text == "Status test 2"
+
+
+def test_files_independence(chat_input_instances):
+    """Test that files attribute is independent between instances."""
+    chat1, chat2 = chat_input_instances
+
+    # Set different files
+    files1 = ["file1.txt", "file2.txt"]
+    files2 = ["file3.txt", "file4.txt"]
+
+    chat1.build(files=files1)
+    chat2.build(files=files2)
+
+    # Verify files are independent
+    assert chat1.files != chat2.files
+    assert chat1.files == files1
+    assert chat2.files == files2