feat(layout): add `LayoutPolar` #90

Job	Run time
Clippy	1m 51s
semver	44s
Rustfmt	14s
Code Coverage	14s
Tests (ubuntu-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	3m 11s
Tests (macos-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	2m 58s
Tests (ubuntu-latest, firefox, plotly_ndarray,plotly_image,static_export_geckodriver,static_expor...	10m 14s
Build Book	3m 42s
Tests (windows-latest, chrome, plotly_ndarray,plotly_image,static_export_chromedriver,debug)	6m 14s
Build Wasm Examples (basic)	54s
Build Examples (customization/consistent_static_format_export)	1m 24s
Build Examples (kaleido)	1m 24s
Build Examples (basic_charts)	31s
Build Examples (3d_charts)	35s
Build Examples (customization/multiple_plots_example)	31s
Build Examples (customization/density_mapbox_example)	27s
Build Examples (maps)	55s
Build Examples (custom_controls)	32s
Build Examples (images)	54s
Build Examples (financial_charts)	25s
Build Examples (ndarray)	29s
Build Examples (subplots)	33s
Build Examples (shapes)	32s
Build Examples (scientific_charts)	32s
Build Wasm Examples (callback-example)	54s
Build Examples (statistical_charts)	35s
Build Examples (themes)	29s
	41m 58s

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