Update permission type

[lukellmann]

• rename ManageEmojis to ManageEmojisAndStickers (renamed in commit discord/discord-api-docs@db5a0cc of PR Document sticker packs, sticker routes, and guild stickers discord/discord-api-docs#3128)
• rename UseSlashCommands to UseApplicationCommands (renamed in commit discord/discord-api-docs@a6ca5e9 of PR User and Message Application Commands discord/discord-api-docs#3614)
• add UseExternalStickers (added in commit discord/discord-api-docs@03626e1 of PR Document sticker packs, sticker routes, and guild stickers discord/discord-api-docs#3128)
• add UseEmbeddedActivities (renamed in rename START_EMBEDDED_ACTIVITIES to USE_EMBEDDED_ACTIVITIES discord/discord-api-docs#4555)
• fix Stream missing in Permission.values
• use shifts instead of hex constants
• add docs

I recommend a commit-wise review.

[lukellmann]

Why is Permission no enum class like other flags? Should we change this?

[HopeBaron]

Because of the Unknown class; in case Discord provided a permission that the user know but we don't

[lukellmann]

Because of the Unknown class; in case Discord provided a permission that the user know but we don't

There is no Unknown class here, it would also be more difficult to use then an Unknown class for some sort of type.

[HopeBaron]

It should have an unknown class; in case we encounter a permission we don't know

[HopeBaron]

I think we had a compiler bug with enums so we decided to use this approach

[lukellmann]

Should I add a Unknown class then? This would mean we also have to change Permissions.values, it currently works by filtering the known values.

[HopeBaron]

the unknown class won't be in the set anyways; it's unknown but it may provide the user with insight given that we hold the full permission set so they can interact with them.

[lukellmann]

the unknown class won't be in the set anyways;

I don't mean Permission.values, I mean Permissions.values (the values of the combined flags).

[lukellmann]

I added a Unknown class.
Also no longer a draft, discord/discord-api-docs#4555 got merged.