feat(layout): add `LayoutPolar` #103

Job	Run time
Clippy	4m 0s
Build Book	3m 40s
Rustfmt	14s
semver	43s
Build Wasm Examples (basic)	52s
Build Wasm Examples (callback-example)	53s
Tests (windows-latest, chrome, plotly_ndarray,plotly_image,static_export_chromedriver,debug)	7m 1s
Code Coverage	11s
Tests (ubuntu-latest, firefox, plotly_ndarray,plotly_image,static_export_geckodriver,static_expor...	3m 20s
Tests (ubuntu-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	3m 20s
Tests (macos-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	3m 46s
Build Examples (3d_charts)	29s
Build Examples (financial_charts)	32s
Build Examples (images)	51s
Build Examples (custom_controls)	30s
Build Examples (customization/multiple_plots_example)	29s
Build Examples (ndarray)	34s
Build Examples (kaleido)	1m 19s
Build Examples (customization/consistent_static_format_export)	1m 25s
Build Examples (basic_charts)	33s
Build Examples (subplots)	32s
Build Examples (maps)	44s
Build Examples (customization/density_mapbox_example)	32s
Build Examples (shapes)	39s
Build Examples (themes)	31s
Build Examples (scientific_charts)	31s
Build Examples (statistical_charts)	34s
	38m 45s

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