fix, refactor: Refactor some code/references in internal Context.

[FayeDel]

About

This pull request essentially:

• Switches input from self.id to self.application_id when editing a message.
  • Essentially as is it fails to edit an ephemeral message.
• Fixes int() to str() typecasting (minor)

Checklist

• The pre-commit code linter has been run over all edited files to ensure the code is linted.
• I've ensured the change(s) work on 3.8.6 and higher.

I've made this pull request: (check all that apply)

• For the documentation
• To add a new feature
• [] As a general enhancement
• As a refactor of the library/the library's code
• To fix an existing bug
• To resolve #ISSUENUMBER

This is:

• A breaking change