xilem_web: Add MemoizedStream view #2486

Job	Run time
cargo check (aarch64-android)	23s
cargo clippy (windows-latest)	50s
cargo check (msrv) (wasm32)	17s
cargo clippy (macos-latest)	47s
cargo check (msrv) (windows-latest)	3m 19s
cargo clippy (ubuntu-latest)	1m 3s
cargo clippy (wasm32)	37s
cargo check (msrv) (macos-latest)	35s
cargo doc	1m 58s
cargo check (msrv) (ubuntu-latest)	44s
formatting	32s
Prime LFS Cache	3s
cargo test (wasm32)	22s
typos	3s
cargo test (windows-latest)	2m 0s
cargo test (macos-latest)	46s
cargo test (ubuntu-latest)	1m 6s
	15m 25s

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