refactor: Remove slot mutex and simplify per blob state #368

Job	Run time
Cross Test (i686-unknown-linux-gnu)	43s
Cross Build Only (x86_64-unknown-freebsd)	47s
Android Build Only (aarch64-linux-android)	29s
Android Build Only (armv7-linux-androideabi)	1m 5s
CI Test Suite / Tests (windows-latest, stable, default, x86_64-pc-windows-msvc)	1m 26s
codespell	7s
Checking docs	1m 5s
cargo deny	23s
CI Test Suite / Tests (windows-latest, stable, none, x86_64-pc-windows-msvc)	1s
check_semver	1m 23s
Minimal Supported Rust Version	1m 14s
CI Test Suite / Tests (macOS-arm-latest, stable, default)	25s
CI Test Suite / Tests (macOS-arm-latest, stable, none)	6s
CI Test Suite / Tests (ubuntu-latest, stable, all)	27s
clippy_check	1m 24s
CI Test Suite / Tests (windows-latest, stable, all, x86_64-pc-windows-msvc)	22s
CI Test Suite / Tests (ubuntu-latest, stable, default)	28s
CI Test Suite / Tests (ubuntu-latest, stable, none)	30s
CI Test Suite / Tests (macOS-arm-latest, stable, all)	1m 50s
Checking fmt	21s
	14m 36s

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