accept str custom_id in component callbacks

[Toricane]

About this Pull Request

This pull request accepts str custom_id in component callbacks, which effectively lets you pass a custom_id instead of a component in the component callback decorator.
See #380, I made this so it targets unstable and also I messed up #380.
this PR does not add anything new, only modifies a couple of lines to accept custom_id in component callbacks.

Checklist

• I've run the pre_push.py script to format and lint the change(s) made.
• I've checked to make sure this pull request runs on Python 3.6.X.
• This fixes/solves something from the project's Issues.
  • Issue (if referenceable):
• This adds something new.
  • This is not a code change.
  • (If required) Relevant documentation has been updated/added.
  • There is/are (a) breaking change(s).

[i0bs]

LGTM.

[i0bs]

Merging this pull request, thank you for your contribution!