add `Deserialize::validate` for non-allocating validation #20478

Job	Run time
Check that packages are publishable	31s
Lints	1m 12s
Check CLI docs	1m 14s
Verify global.json files are symlinks	1m 5s
Check for Python smoketest edits	10s
Test spacetimedb-update flow (x86_64-pc-windows-msvc)	1m 8s
Check CI command docs	1m 11s
Check smoketests/mod.rs is complete	1m 10s
Test spacetimedb-update flow (aarch64-unknown-linux-gnu)	51s
Test spacetimedb-update flow (x86_64-unknown-linux-gnu)	1m 8s
Test spacetimedb-update flow (aarch64-apple-darwin)	1m 12s
Build and test wasm bindings	1m 11s
Unreal Engine Tests	-1s
Verify LLM benchmark is up to date	-1s
Test Suite	1s
Internal Tests	1s
csharp-testsuite	1s
unity-testsuite	1s
Smoketests (${{ matrix.name }})	1s
	12m 6s

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