Introduce `MastForestStore` #4860

Job	Run time
rustfmt	15s
Clippy	1m 14s
Check Rust stable on ubuntu with --all-targets --no-default-features	1m 20s
Check Rust stable on ubuntu with --all-targets	1m 20s
no-std (stable, wasm32-unknown-unknown)	1m 40s
Test Rust nightly on windows-2022	0s
Check Rust stable on ubuntu with --all-targets --all-features	1m 12s
Test Rust stable on ubuntu with --profile test-release	10m 43s
Check Rust nightly on ubuntu with --all-targets --no-default-features	1m 11s
no-std (nightly, wasm32-unknown-unknown)	1m 28s
Test Rust stable on ubuntu with --profile test-release --doc	5m 41s
Test Rust nightly on ubuntu with --profile test-release	9m 54s
Check Rust nightly on ubuntu with --all-targets	1m 15s
Check Rust nightly on ubuntu with --all-targets --all-features	1m 19s
Test Rust nightly on ubuntu with --profile test-release --doc	5m 46s
	44m 18s

Provide feedback