Split layout into multiple modules #521

Job	Run time
Clippy	53s
semver	40s
Rustfmt	14s
Tests (macos-latest)	54s
Tests (windows-latest)	39s
Code Coverage	10s
Build Wasm Examples (basic)	50s
Tests (ubuntu-latest)	52s
Build Wasm Examples (callback-example)	52s
Build Examples (3d_charts)	23s
Build Examples (custom_controls)	32s
Build Examples (financial_charts)	25s
Build Examples (images)	37s
Build Examples (shapes)	24s
Build Examples (scientific_charts)	22s
Build Examples (ndarray)	31s
Build Examples (maps)	22s
Build Examples (subplots)	22s
Build Examples (kaleido)	52s
Build Examples (basic_charts)	26s
	11m 20s

Provide feedback