Remove redundant fields from Context #1080

Job	Run time
Rustfmt	7s
Clippy	45s
Test (MSRV)	1m 17s
Build docs	1m 26s
Test (stable)	2m 10s
Test (beta)	2m 0s
Test (nightly)	1m 41s
Test (macOS)	1m 51s
Test (Windows)	5m 9s
Test (no features)	1m 27s
Test (all features - simdjson, cargo test --all-features --lib --tests --examples)	1m 15s
Test (native TLS, cargo test --all-features --features serenity/native_tls_backend --lib --tests ...	1m 12s
	20m 20s

Provide feedback