Add guild member flags

[NoComment1105]

discord/discord-api-docs#5874
I don't think this is everything, let me know if it isn't

[lukellmann]

2023-02-16T12:09:07.8811675Z GuildTest > GuildMember serialization() FAILED
2023-02-16T12:09:07.8812964Z     kotlinx.serialization.MissingFieldException: Field 'flags' is required for type with serial name 'dev.kord.common.entity.DiscordGuildMember', but it was missing at path: $
2023-02-16T12:09:07.8814057Z         at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:90)
2023-02-16T12:09:07.8815009Z         at kotlinx.serialization.json.Json.decodeFromString(Json.kt:95)
2023-02-16T12:09:07.8815479Z         at json.GuildTest.GuildMember serialization(GuildTest.kt:80)
2023-02-16T12:09:07.8815735Z 
2023-02-16T12:09:07.8815846Z         Caused by:
2023-02-16T12:09:07.8816691Z         kotlinx.serialization.MissingFieldException: Field 'flags' is required for type with serial name 'dev.kord.common.entity.DiscordGuildMember', but it was missing
2023-02-16T12:09:07.8817493Z             at kotlinx.serialization.internal.PluginExceptionsKt.throwMissingFieldException(PluginExceptions.kt:20)
2023-02-16T12:09:07.8818160Z             at dev.kord.common.entity.DiscordGuildMember.<init>(Member.kt:10)
2023-02-16T12:09:07.8818687Z             at dev.kord.common.entity.DiscordGuildMember$$serializer.deserialize(Member.kt:10)
2023-02-16T12:09:07.8819214Z             at dev.kord.common.entity.DiscordGuildMember$$serializer.deserialize(Member.kt:10)
2023-02-16T12:09:07.8819919Z             at kotlinx.serialization.json.internal.StreamingJsonDecoder.decodeSerializableValue(StreamingJsonDecoder.kt:70)
2023-02-16T12:09:07.8820447Z             ... 2 more

[NoComment1105]

Fixed tests i think