feat: select menu default values

[shiftinv]

Summary

discord/discord-api-docs@515931a

This implements the new default_values field for auto-populated (i.e. non-string) select menus. The PR is pretty much finished, but it could use some more testing.

Note that this doesn't currently implement message.resolved, which contains resolved objects for components[*].default_values. We have nowhere to put this data right now, since component objects store plain SelectDefaultValues, but implementing it in the future would be pretty simple. The data isn't all that useful in most cases, anyway.

Checklist

• If code changes were made, then they have been tested
  • I have updated the documentation to reflect the changes
  • I have formatted the code properly by running pdm lint
  • I have type-checked the code by running pdm pyright
• This PR fixes an issue
• This PR adds something new (e.g. new method or parameters)
• This PR is a breaking change (e.g. methods or parameters removed/renamed)
• This PR is not a code change (e.g. documentation, README, ...)