Missing Voice REST methods

[KiloOscarSix]

https://discord.com/developers/docs/resources/voice#get-current-user-voice-state
https://discord.com/developers/docs/resources/voice#get-user-voice-state

If the implementation is as simple as,

/// Returns the specified user's voice state in the guild
    pub async fn get_voice_state(&self, guild_id: GuildId, user_id: UserId) -> Result<VoiceState> {
        self.fire(Request {
            body: None,
            multipart: None,
            headers: None,
            method: LightMethod::Get,
            route: Route::GuildVoiceStates { guild_id, user_id },
            params: None,
        })
        .await
    }

I can open a PR after work, however opening this issue in case there are any specific implementation details I'm missing.