iterinliner: rename captured locals inside closures in a copied for body

[tokyovigilante]

When an inline iterator is expanded, each yield gets a copy of the for body with fresh names for the locals and labels it declares (collectDefs + copyFreshened). copyFreshened copied nested routines verbatim, so a closure declared in the body kept referring to the body's locals by their OLD names; the declarations were renamed away and a later pass hit [Bug] could not find symbol: v.0:

proc populate(n: int): int =
  result = 0
  for d in 0 ..< n:
    var v = d
    proc fill(): int {.closure.} = v
    result += fill()

Nested routines are now copied through the same renaming, which touches only the enclosing body's names (the mapping holds nothing the routine declares itself). Each copy also gets its own name for the routine, so an iterator with several yields does not define one closure symbol per copy under a single name. The same path serves expandInlineIterator, so a closure inside an inline iterator's body capturing the iterator's own locals is fixed too. Templates, macros, types and pragmas are still copied verbatim.