Merge tests into a larger file (part 1 of ∞) (#9318)

* merge actiontable tests

* merge arithm tests

* merge array tests

* merge assign tests

* merge bind tests

* merge casestmt tests

* merge closure tests

* merge cnt seq tests

* merge collections tests

* merge concept issues tests

* merge concept tests

* fix failing tests

* smaller outputs

Use `doAssert` where possible.

* fix wrong output

* split `tcomputedgoto`

* revert merging concepts

* fix failing test

tests/collections/tcollections.nim

@@ -0,0 +1,56 @@
+discard """
+  file: "tcollections.nim"
+  output: '''
+'''
+"""
+
+import deques, sequtils
+
+
+block tapply:
+  var x = @[1, 2, 3]
+  x.apply(proc(x: var int) = x = x+10)
+  x.apply(proc(x: int): int = x+100)
+  x.applyIt(it+5000)
+  doAssert x == @[5111, 5112, 5113]
+
+
+block tdeques:
+  proc index(self: Deque[int], idx: Natural): int =
+    self[idx]
+
+  proc main =
+    var testDeque = initDeque[int]()
+    testDeque.addFirst(1)
+    assert testDeque.index(0) == 1
+
+  main()
+
+
+block tmapit:
+  var x = @[1, 2, 3]
+  # This mapIt call will run with preallocation because ``len`` is available.
+  var y = x.mapIt($(it+10))
+  doAssert y == @["11", "12", "13"]
+
+  type structureWithoutLen = object
+    a: array[5, int]
+
+  iterator items(s: structureWithoutLen): int {.inline.} =
+    yield s.a[0]
+    yield s.a[1]
+    yield s.a[2]
+    yield s.a[3]
+    yield s.a[4]
+
+  var st: structureWithoutLen
+  st.a[0] = 0
+  st.a[1] = 1
+  st.a[2] = 2
+  st.a[3] = 3
+  st.a[4] = 4
+
+  # this will run without preallocating the result
+  # since ``len`` is not available
+  var r = st.mapIt($(it+10))
+  doAssert r == @["10", "11", "12", "13", "14"]