Add support for premium buttons #901

Job	Run time
Test (macOS)	1m 40s
Test (nightly)	3m 9s
Test (stable)	3m 26s
Test (beta)	3m 16s
Test (Windows)	4m 26s
Examples	3m 3s
Build docs	22s
Test (native-tls)	2m 59s
Test (no default features)	50s
Test (no cache)	3m 0s
Check minimal versions	31s
Test (no gateway)	1m 43s
MSRV	0s
Test (unstable Discord API features)	3m 21s
Test (simd-json)	3m 22s
Test (chrono, chrono)	53s
Test (unstable API + typesize, default unstable_discord_api typesize, true)	55s
Test (builder without model, builder, true)	25s
Test (unstable Discord API (no default features), unstable_discord_api, true)	28s
	37m 49s

Provide feedback