cString => cSourceString; tyCString => tyCstring so that error msgs show cstring, not cString (#17744)

lib/core/typeinfo.nim

@@ -322,12 +322,12 @@ proc base*(x: Any): Any =
 proc isNil*(x: Any): bool =
   ## `isNil` for an `x` that represents a cstring, proc or
   ## some pointer type.
-  assert x.rawType.kind in {tyCString, tyRef, tyPtr, tyPointer, tyProc}
+  assert x.rawType.kind in {tyCstring, tyRef, tyPtr, tyPointer, tyProc}
   result = isNil(cast[ppointer](x.value)[])
 
 const pointerLike =
-  when defined(gcDestructors): {tyCString, tyRef, tyPtr, tyPointer, tyProc}
-  else: {tyString, tyCString, tyRef, tyPtr, tyPointer, tySequence, tyProc}
+  when defined(gcDestructors): {tyCstring, tyRef, tyPtr, tyPointer, tyProc}
+  else: {tyString, tyCstring, tyRef, tyPtr, tyPointer, tySequence, tyProc}
 
 proc getPointer*(x: Any): pointer =
   ## Retrieves the pointer value out of `x`. `x` needs to be of kind
@@ -669,7 +669,7 @@ proc setString*(x: Any, y: string) =
 
 proc getCString*(x: Any): cstring =
   ## Retrieves the `cstring` value out of `x`. `x` needs to represent a `cstring`.
-  assert x.rawType.kind == tyCString
+  assert x.rawType.kind == tyCstring
   result = cast[ptr cstring](x.value)[]
 
 proc assign*(x, y: Any) =

lib/system/assign.nim

@@ -167,7 +167,7 @@ when false:
     of tyPointer: k = "range"
     of tyOpenArray: k = "openarray"
     of tyString: k = "string"
-    of tyCString: k = "cstring"
+    of tyCstring: k = "cstring"
     of tyInt: k = "int"
     of tyInt32: k = "int32"
     else: k = "other"

lib/system/hti.nim

@@ -40,7 +40,7 @@ type
     tyPointer,
     tyOpenArray,
     tyString,
-    tyCString,
+    tyCstring,
     tyForward,
     tyInt,
     tyInt8,

lib/system/repr.nim

@@ -281,7 +281,7 @@ when not defined(useNimRtl):
     of tyString:
       let sp = cast[ptr string](p)
       reprStrAux(result, sp[].cstring, sp[].len)
-    of tyCString:
+    of tyCstring:
       let cs = cast[ptr cstring](p)[]
       if cs.isNil: add result, "nil"
       else: reprStrAux(result, cs, cs.len)

lib/system/reprjs.nim

@@ -200,7 +200,7 @@ proc reprAux(result: var string, p: pointer, typ: PNimType,
     var fp: int
     {. emit: "`fp` = `p`;\n" .}
     add(result, reprStr(cast[string](p)))
-  of tyCString:
+  of tyCstring:
     var fp: cstring
     {. emit: "`fp` = `p`;\n" .}
     if fp.isNil: