feat(layout): add `LayoutPolar` #102

Job	Run time
Clippy	4m 3s
Tests (ubuntu-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	3m 3s
Rustfmt	16s
Tests (macos-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	4m 18s
Code Coverage	13s
semver	45s
Build Examples (3d_charts)	33s
Build Examples (basic_charts)	34s
Tests (ubuntu-latest, firefox, plotly_ndarray,plotly_image,static_export_geckodriver,static_expor...	3m 47s
Build Wasm Examples (basic)	55s
Build Wasm Examples (callback-example)	57s
Build Book	3m 29s
Build Examples (customization/consistent_static_format_export)	1m 27s
Build Examples (custom_controls)	35s
Build Examples (shapes)	35s
Build Examples (scientific_charts)	30s
Build Examples (themes)	29s
Build Examples (financial_charts)	31s
Build Examples (customization/multiple_plots_example)	31s
Build Examples (kaleido)	1m 13s
Tests (windows-latest, chrome, plotly_ndarray,plotly_image,static_export_chromedriver,debug)	6m 41s
Build Examples (statistical_charts)	35s
Build Examples (ndarray)	31s
Build Examples (maps)	46s
Build Examples (subplots)	31s
Build Examples (images)	51s
Build Examples (customization/density_mapbox_example)	24s
	39m 3s

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