When loading suppression comments from tokens, fix the token lookback
to look far enough back to find an indent token that isn't matched by
a dedent token. This prevents the system from marking "enable" comments
as having "invalid indentation".

Fix #22869

* main: (76 commits)
  [ty] Improve the check for `NewType`s with generic bases (#22961)
  [ty] Ban legacy `TypeVar` bounds or constraints from containing type variables (#22949)
  Bump the typing conformance suite pin (#22960)
  [ty] Emit an error if a TypeVarTuple is used to subscript `Generic` or `Protocol` without being unpacked (#22952)
  [ty] Reduce false positives when subscripting classes generic over `TypeVarTuple`s (#22950)
  [ty] Detect invalid attempts to subclass `Protocol[]` and `Generic[]` simultaneously (#22948)
  Fix suppression indentation matching (#22903)
  Remove hidden `--output-format` warning (#22944)
  [ty] Validate signatures of dataclass `__post_init__` methods (#22730)
  [ty] extend special-cased `numbers` diagnostic to `invalid-argument-type` errors (#22938)
  [ty] Avoid false positive for `not-iterable` with no-positive intersection types (#22089)
  [ty] Preserve pure negation types in descriptor protocol (#22907)
  [ty] add special-case diagnostic for `numbers` module (#22931)
  [ty] Move the location of more `invalid-overload` diagnostics (#22933)
  [ty] Fix unary and comparison operators for TypeVars with union bounds (#22925)
  [ty] Rule Selection: ignore/warn/select all rules (unless subsequently overriden) (#22832)
  [ty] Fix TypedDict construction from existing TypedDict values (#22904)
  [ty] fix bug in string annotations and clean up diagnostics (#22913)
  [ty] Improve support for goto-type, goto-declaration, hover, and highlighting of string annotations (#22878)
  [ty] Rename old typing imports to new on `unresolved-reference`. (#22827)
  ...