docs: document new KVStore features, add some edge case tests #4883

Job	Run time
check-changelog	10s
check-docusaurus	24m 43s
Ensure that all required "cargo install" commands are run, or we have a cache hit (viceroy, 0.12.1)	7s
format	17s
Ensure that all required "cargo install" commands are run, or we have a cache hit (wasm-tools, 1....	5s
shellcheck	6s
Debug Build	3m 35s
Build (release)	8m 13s
Build (weval)	5m 45s
Run Web Platform Tests Debug	4m 24s
sdktest-debug (viceroy)	1m 34s
sdktest-debug (compute)	5m 40s
Run Web Platform Tests (release)	1m 24s
test-npm-package (18, ubuntu-latest)	31s
Run Web Platform Tests (weval)	1m 14s
test-npm-package (22, ubuntu-latest)	30s
test-npm-package (22, windows-latest)	1m 7s
test-npm-package (22, macos-latest)	38s
sdktest (compute, release)	4m 38s
sdktest (compute, weval)	5m 46s
sdktest (viceroy, release)	54s
sdktest (viceroy, weval)	1m 25s
	1h 12m 46s

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