feat(layout): add `LayoutPolar` #86

Job	Run time
Build Book	3m 46s
Tests (macos-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	3m 28s
Tests (ubuntu-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	2m 26s
Rustfmt	14s
Build Wasm Examples (callback-example)	1m 11s
Tests (ubuntu-latest, firefox, plotly_ndarray,plotly_image,static_export_geckodriver,static_expor...	2m 24s
Build Wasm Examples (basic)	53s
Clippy	1m 51s
Tests (windows-latest, chrome, plotly_ndarray,plotly_image,static_export_chromedriver,debug)	5m 9s
semver	47s
Build Examples (3d_charts)	30s
Code Coverage	11s
Build Examples (customization/consistent_static_format_export)	1m 52s
Build Examples (basic_charts)	32s
Build Examples (scientific_charts)	27s
Build Examples (ndarray)	43s
Build Examples (kaleido)	1m 13s
Build Examples (financial_charts)	29s
Build Examples (customization/density_mapbox_example)	32s
Build Examples (maps)	46s
Build Examples (subplots)	33s
Build Examples (themes)	30s
Build Examples (shapes)	42s
Build Examples (images)	47s
Build Examples (custom_controls)	34s
Build Examples (customization/multiple_plots_example)	32s
Build Examples (statistical_charts)	43s
	33m 45s

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