feat(UserFlags): add renamed UserFlags

[NotSugden]

Please describe the changes this PR makes and why it should be merged:
user flags DISCORD_PARTNER and VERIFIED_DEVELOPER have been renamed, this PR reflects those changes by deprecating the old names, and adding the renamed flags

see discord/discord-api-docs#2011
Status

• Code changes have been tested against the Discord API, or there are no code changes
• I know how to update typings and have done so, or typings don't need updating

Semantic versioning classification:

• This PR changes the library's interface (methods or parameters added)
  • This PR includes breaking changes (methods removed or renamed, parameters moved or removed)
• This PR only includes non-code changes, like changes to documentation, README, etc.

[sighbaby]

Reviewed