xilem_web: Add MemoizedStream view #2255

Job	Run time
cargo check (msrv) (wasm32)	18s
cargo check (msrv) (windows-latest)	1m 56s
cargo clippy (windows-latest)	1m 17s
cargo check (aarch64-android)	22s
cargo check (msrv) (macos-latest)	39s
cargo clippy (macos-latest)	1m 16s
cargo check (msrv) (ubuntu-latest)	46s
cargo clippy (wasm32)	43s
cargo clippy (ubuntu-latest)	30s
cargo doc	31s
formatting	31s
Prime LFS Cache	4s
cargo test (wasm32)	23s
typos	6s
cargo test (windows-latest)	2m 1s
cargo test (macos-latest)	44s
cargo test (ubuntu-latest)	1m 15s
	13m 22s

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