Closes parts of #4459

• Added the ability to specify a payload in sendPaidMedia that is received back by the bot in TransactionPartnerUser and purchased_paid_media updates. (Taken by @aelkheir)
• Added the field prize_star_count to the classes GiveawayCreated, Giveaway, GiveawayWinners and ChatBoostSourceGiveaway. (Taken by @aelkheir)
• Added the field is_star_giveaway to the class GiveawayCompleted. (Taken by @aelkheir)

Checklist for PRs

• Added .. versionadded:: NEXT.VERSION, .. versionchanged:: NEXT.VERSION, .. deprecated:: NEXT.VERSION or .. versionremoved:: NEXT.VERSION to the docstrings for user facing changes (for methods/class descriptions, arguments and attributes)
• Created new or adapted existing unit tests
• Documented code changes according to the CSI standard <https://standards.mousepawmedia.com/en/stable/csi.html>__
• Added myself alphabetically to AUTHORS.rst (optional)
• Checked the Stability Policy <https://docs.python-telegram-bot.org/stability_policy.html>_ in case of deprecations or changes to documented behavior

If the PR contains API changes (otherwise, you can ignore this passage)

• Checked the Bot API specific sections of the Stability Policy <https://docs.python-telegram-bot.org/stability_policy.html>_
• Created a PR to remove functionality deprecated in the previous Bot API release (see here <https://docs.python-telegram-bot.org/en/stable/stability_policy.html#case-2>_)
• New classes:
  • Added self._id_attrs and corresponding documentation
  • __init__ accepts api_kwargs as kw-only
• Added new shortcuts:
  • In :class:~telegram.Chat & :class:~telegram.User for all methods that accept chat/user_id
• If relevant:
  • Link new and existing constants in docstrings instead of hard-coded numbers and strings
  • Added or updated documentation for the changed class(es) and/or method(s)