refactor: Remove slot mutex and simplify per blob state #382

Job	Run time
Cross Build Only (x86_64-unknown-freebsd)	51s
cargo deny	27s
CI Test Suite / Tests (windows-latest, stable, all, x86_64-pc-windows-msvc)	1m 59s
CI Test Suite / Tests (windows-latest, stable, default, x86_64-pc-windows-msvc)	2m 4s
CI Test Suite / Tests (ubuntu-latest, stable, default)	1m 35s
CI Test Suite / Tests (windows-latest, stable, none, x86_64-pc-windows-msvc)	2m 1s
CI Test Suite / Tests (ubuntu-latest, stable, none)	1m 27s
CI Test Suite / Tests (ubuntu-latest, stable, all)	1m 19s
CI Test Suite / Tests (macOS-arm-latest, stable, none)	1m 35s
Android Build Only (aarch64-linux-android)	1m 9s
Minimal Supported Rust Version	1m 0s
codespell	5s
CI Test Suite / Tests (macOS-arm-latest, stable, all)	1m 43s
Android Build Only (armv7-linux-androideabi)	1m 9s
Checking fmt	26s
Checking docs	1m 6s
clippy_check	1m 43s
check_semver	1m 4s
CI Test Suite / Tests (macOS-arm-latest, stable, default)	1m 34s
Cross Test (i686-unknown-linux-gnu)	1m 26s
	25m 43s

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