feat(CommandInteraction): add support for localized slash commands

[suneettipirneni]

Please describe the changes this PR makes and why it should be merged:

Add support for localized names and descriptions in slash command payloads.

Status and versioning classification:

• 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

[ImRodry]

Discord API docs PR discord/discord-api-docs#4653

[ImRodry]

Missed the edit methods in ApplicationCommand (also please provide some examples in those)

[FedorLap2006]

LGTM. However, docs state that behaviour of GET endpoints is changed, therefore they won't return name_localizations & description_localizations by default, instead they will return name_localized & description_localized, which are not included in the PR. The way this behaviour could be altered is by supplying ?with_localizations=true. Not sure what's the best solution here though.

[suneettipirneni]

LGTM. However, docs state that behaviour of GET endpoints is changed, therefore they won't return name_localizations & description_localizations by default, instead they will return name_localized & description_localized, which are not included in the PR. The way this behaviour could be altered is by supplying ?with_localizations=true. Not sure what's the best solution here though.

I can add it as an option in the ApplicationCommandManager

[FedorLap2006]

I can add it as an option in the ApplicationCommandManager

Problem is, when it's set to false (i.e. endpoint provides localized fields) you would need to pass an additional header to alter the language. Which I'm not sure where would be the best to put a setting for

[kyranet]

There are merge conflicts, please update or rebase your branch.