Add `plotly_static` `async` API #67

Job	Run time
Clippy	1m 20s
Rustfmt	15s
semver	42s
Build Book	3m 27s
Build Wasm Examples (callback-example)	1m 1s
Code Coverage	11s
Build Wasm Examples (basic)	55s
Tests (ubuntu-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	3m 22s
Tests (macos-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	2m 45s
Tests (ubuntu-latest, firefox, plotly_ndarray,plotly_image,static_export_geckodriver,static_expor...	2m 6s
Tests (windows-latest, chrome, plotly_ndarray,plotly_image,static_export_chromedriver,debug)	4m 36s
Build Examples (basic_charts)	37s
Build Examples (custom_controls)	35s
Build Examples (customization/consistent_static_format_export)	1m 26s
Build Examples (3d_charts)	32s
Build Examples (customization/multiple_plots_example)	44s
Build Examples (financial_charts)	38s
Build Examples (images)	53s
Build Examples (customization/density_mapbox_example)	40s
Build Examples (ndarray)	33s
Build Examples (shapes)	40s
Build Examples (maps)	46s
Build Examples (statistical_charts)	40s
Build Examples (scientific_charts)	35s
Build Examples (kaleido)	1m 25s
Build Examples (subplots)	33s
Build Examples (themes)	51s
	32m 48s

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