Introduce new Chunk iteration APIs #15684

Job	Run time
paths-filter	8s
Checks / Rerun lints	41s
Checks / Check if running codegen would produce any changes	53s
Checks / Lint markdown	23s
Checks / Misc formatting	20s
Checks / markdown-paths-filter	4s
Checks / Spell Check	8s
Checks / Check links	0s
C++ tests	0s
Python Checks	0s
Deploy Landing Preview	0s
Minimum CLI Build / Set Config (linux-x64)	4s
Build rerun_js / Build rerun_js	3m 1s
Rust Checks / Test on ${{ matrix.name }}	0s
Rust Checks / Rust lints (fmt, check, clippy, tests, doc)	4m 14s
Build web viewer / Build web viewer	3m 5s
Minimum CLI Build / Build rerun-cli (ubuntu-latest-16-cores)	4m 48s
Upload Web / Upload web build to google cloud (wasm32 + wasm-bindgen)	9s
Minimum Wheel Build	0s
Minimum Wheel Test	0s
	17m 58s

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