Introduce `MastForestStore` #4896

Job	Run time
Clippy	1m 17s
rustfmt	14s
no-std (stable, wasm32-unknown-unknown)	1m 41s
no-std (nightly, wasm32-unknown-unknown)	1m 39s
Check Rust stable on ubuntu with --all-targets --no-default-features	1m 18s
Check Rust stable on ubuntu with --all-targets	1m 8s
Test Rust nightly on windows-2022	0s
Check Rust stable on ubuntu with --all-targets --all-features	1m 27s
Test Rust stable on ubuntu with --profile test-release	10m 12s
Check Rust nightly on ubuntu with --all-targets --no-default-features	1m 11s
Test Rust stable on ubuntu with --profile test-release --doc	5m 52s
Check Rust nightly on ubuntu with --all-targets	1m 17s
Test Rust nightly on ubuntu with --profile test-release	11m 19s
Check Rust nightly on ubuntu with --all-targets --all-features	1m 20s
Test Rust nightly on ubuntu with --profile test-release --doc	6m 28s
	46m 23s

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