refactor: Remove slot mutex and simplify per blob state #489

Job	Run time
Android Build Only (armv7-linux-androideabi)	1m 11s
Cross Test (i686-unknown-linux-gnu)	1m 40s
Cross Build Only (x86_64-unknown-freebsd)	51s
Android Build Only (aarch64-linux-android)	1m 10s
Minimal Supported Rust Version	59s
Checking docs	53s
Checking fmt	26s
clippy_check	1m 21s
codespell	6s
CI Test Suite / Tests (windows-latest, stable, none, x86_64-pc-windows-msvc)	2m 2s
CI Test Suite / Tests (windows-latest, stable, all, x86_64-pc-windows-msvc)	2m 2s
cargo deny	28s
CI Test Suite / Tests (windows-latest, stable, default, x86_64-pc-windows-msvc)	2m 3s
check_semver	1m 31s
CI Test Suite / Tests (macOS-arm-latest, stable, default)	1m 35s
CI Test Suite / Tests (ubuntu-latest, stable, none)	1m 17s
CI Test Suite / Tests (ubuntu-latest, stable, all)	1m 28s
CI Test Suite / Tests (macOS-arm-latest, stable, none)	1m 35s
CI Test Suite / Tests (ubuntu-latest, stable, default)	1m 31s
CI Test Suite / Tests (macOS-arm-latest, stable, all)	1m 41s
	25m 50s

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