refactor: Remove slot mutex and simplify per blob state #367

Job	Run time
Android Build Only (aarch64-linux-android)	1m 26s
Checking fmt	21s
codespell	6s
cargo deny	27s
CI Test Suite / Tests (windows-latest, stable, all, x86_64-pc-windows-msvc)	5m 43s
Android Build Only (armv7-linux-androideabi)	1m 6s
check_semver	1m 14s
Checking docs	1m 6s
CI Test Suite / Tests (windows-latest, stable, none, x86_64-pc-windows-msvc)	1s
CI Test Suite / Tests (ubuntu-latest, stable, all)	30s
Minimal Supported Rust Version	1m 22s
Cross Build Only (x86_64-unknown-freebsd)	48s
CI Test Suite / Tests (macOS-arm-latest, stable, none)	35s
CI Test Suite / Tests (ubuntu-latest, stable, default)	30s
CI Test Suite / Tests (windows-latest, stable, default, x86_64-pc-windows-msvc)	1s
CI Test Suite / Tests (macOS-arm-latest, stable, default)	34s
clippy_check	1m 23s
CI Test Suite / Tests (macOS-arm-latest, stable, all)	35s
Cross Test (i686-unknown-linux-gnu)	52s
CI Test Suite / Tests (ubuntu-latest, stable, none)	30s
	19m 10s

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