Support simd_json (#105)

This PR adds support for the simd-json library whenever decoding or encoding JSON responses. This may be enabled independently of serenity and twilight support for SIMD acceleration.

Co-authored-by: Kyle Simpson <kyleandrew.simpson@gmail.com>

src/input/adapters/cached/error.rs

@@ -1,6 +1,5 @@
-use crate::input::AudioStreamError;
+use crate::{error::JsonError, input::AudioStreamError};
 use audiopus::error::Error as OpusError;
-use serde_json::Error as JsonError;
 use std::{
     error::Error as StdError,
     fmt::{Display, Formatter, Result as FmtResult},