Add `plotly_static` `async` API #60

Job	Run time
Rustfmt	16s
Clippy	1m 23s
Build Wasm Examples (basic)	56s
semver	42s
Build Wasm Examples (callback-example)	54s
Code Coverage	22s
Tests (ubuntu-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	3m 12s
Tests (macos-latest, chrome, plotly_ndarray,plotly_image,static_export_default,debug)	3m 32s
Tests (ubuntu-latest, firefox, plotly_ndarray,plotly_image,static_export_geckodriver,static_expor...	3m 16s
Tests (windows-latest, chrome, plotly_ndarray,plotly_image,static_export_chromedriver,debug)	3m 54s
Build Examples (custom_controls)	34s
Build Book	3m 33s
Build Examples (basic_charts)	34s
Build Examples (customization/consistent_static_format_export)	1m 30s
Build Examples (3d_charts)	36s
Build Examples (customization/density_mapbox_example)	33s
Build Examples (shapes)	37s
Build Examples (scientific_charts)	33s
Build Examples (financial_charts)	37s
Build Examples (subplots)	35s
Build Examples (images)	51s
Build Examples (customization/multiple_plots_example)	36s
Build Examples (maps)	44s
Build Examples (ndarray)	33s
Build Examples (statistical_charts)	34s
Build Examples (kaleido)	1m 23s
Build Examples (themes)	35s
	33m 25s

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