[pjeweb]

Closes #1563.

Currently

When a font in a style's text-font is not available, ol-mapbox-style loads a stylesheet for it from Fontsource on jsDelivr. Applications can redirect or reduce these requests, but not turn them off:

• The style publisher points ol:webfonts to fonts it hosts, as the README describes. basemap.de, for example, does not do this yet.
• The application points the webfonts option to its own server. Every face it does not host is still requested there and fails with a 404, once per face and page load.
• The application loads the style's fonts with CSS, or rewrites the style's text-font values to fonts it already has. A face that a style update adds or renames is then fetched from the CDN again.

Wanted

A switch that lets an application turn automatic font loading off:

• Labels use the fonts the page provides.
• No font requests are made, so none go to third parties and none are expected to fail with a 404.
• Nothing has to be kept in sync when the style changes.

Implemented Change

With webfonts: false passed to apply() or applyStyle():

• ol-mapbox-style adds no font stylesheets.
• Labels use the fonts the page provides, including any the application mapped by rewriting text-font.
• Faces the page does not provide use the browser's default font. This also holds for faces that a later style update adds or renames.
• Styles with ol:webfonts metadata are the exception: their fonts still load from that location.

Without the option, nothing changes, so maps keep their intended fonts.

[ahocevar]

Please address my inline comments, and simplify the tests accordingly, avoiding test bloat.

[ahocevar]

I'd rather not support metadata['ol:webfonts'] set to false.

[ahocevar]

templateUrl already has the value of options.webfonts here, so this change is not necessary.

[pjeweb]

I removed the metadata opt-out and redundant apply.js logic, rebased onto main, reduced the tests to one case, and rewrote the description.