refactor: Remove slot mutex and simplify per blob state #370

Job	Run time
Android Build Only (aarch64-linux-android)	1m 10s
Cross Test (i686-unknown-linux-gnu)	1m 25s
Cross Build Only (x86_64-unknown-freebsd)	51s
Android Build Only (armv7-linux-androideabi)	1m 10s
clippy_check	1m 30s
Minimal Supported Rust Version	1m 21s
codespell	5s
Checking docs	1m 5s
check_semver	1m 9s
cargo deny	26s
CI Test Suite / Tests (windows-latest, stable, all, x86_64-pc-windows-msvc)	2m 4s
Checking fmt	26s
CI Test Suite / Tests (ubuntu-latest, stable, all)	1m 20s
CI Test Suite / Tests (windows-latest, stable, default, x86_64-pc-windows-msvc)	2m 2s
CI Test Suite / Tests (windows-latest, stable, none, x86_64-pc-windows-msvc)	2m 0s
CI Test Suite / Tests (ubuntu-latest, stable, none)	1m 30s
CI Test Suite / Tests (ubuntu-latest, stable, default)	1m 24s
CI Test Suite / Tests (macOS-arm-latest, stable, all)	1m 40s
CI Test Suite / Tests (macOS-arm-latest, stable, none)	1m 37s
CI Test Suite / Tests (macOS-arm-latest, stable, default)	1m 34s
	25m 49s

Provide feedback