Add get sticker pack endpoint (#376)

Author: sebm253

rest/rest_endpoints.go

@@ -229,6 +229,7 @@ var (
 // Stickers
 var (
 	GetNitroStickerPacks = NewEndpoint(http.MethodGet, "/sticker-packs")
+	GetNitroStickerPack  = NewEndpoint(http.MethodGet, "/sticker-packs/{pack.id}")
 	GetSticker           = NewEndpoint(http.MethodGet, "/stickers/{sticker.id}")
 	GetGuildStickers     = NewEndpoint(http.MethodGet, "/guilds/{guild.id}/stickers")
 	CreateGuildSticker   = NewEndpoint(http.MethodPost, "/guilds/{guild.id}/stickers")

rest/stickers.go

@@ -14,6 +14,7 @@ func NewStickers(client Client) Stickers {
 
 type Stickers interface {
 	GetNitroStickerPacks(opts ...RequestOpt) ([]discord.StickerPack, error)
+	GetNitroStickerPack(packID snowflake.ID, opts ...RequestOpt) (*discord.StickerPack, error)
 	GetSticker(stickerID snowflake.ID, opts ...RequestOpt) (*discord.Sticker, error)
 	GetStickers(guildID snowflake.ID, opts ...RequestOpt) ([]discord.Sticker, error)
 	CreateSticker(guildID snowflake.ID, createSticker discord.StickerCreate, opts ...RequestOpt) (*discord.Sticker, error)
@@ -34,6 +35,11 @@ func (s *stickerImpl) GetNitroStickerPacks(opts ...RequestOpt) (stickerPacks []d
 	return
 }
 
+func (s *stickerImpl) GetNitroStickerPack(packID snowflake.ID, opts ...RequestOpt) (pack *discord.StickerPack, err error) {
+	err = s.client.Do(GetNitroStickerPack.Compile(nil, packID), nil, &pack, opts...)
+	return
+}
+
 func (s *stickerImpl) GetSticker(stickerID snowflake.ID, opts ...RequestOpt) (sticker *discord.Sticker, err error) {
 	err = s.client.Do(GetSticker.Compile(nil, stickerID), nil, &sticker, opts...)
 	return