feat(schemas/browsers)!: merge accepts_{flags,webextension} fields into accepts array

[caugner]

Summary

Merges the accepts_flags and accepts_webextensions fields in the browser schema into a single accepts object with boolean properties flags and webextensions.

Important

This is a breaking change, as we expose these fields in the built data.json.

Test results and supporting details

Prepares for #25804, which adds webdriver-bidi.

Related issues

[queengooborg]

Considering that we're adding more flags for featuresets browsers allow, this makes sense.

Small nit: perhaps it would make more sense to make this a dictionary instead, so that we can add version numbers for when a featureset was introduced?

[caugner]

Small nit: perhaps it would make more sense to make this a dictionary instead, so that we can add version numbers for when a featureset was introduced?

@queengooborg I'm open to discussing the use case behind making this a dictionary, but I would prefer to start with this basic approach, to avoid scope creep.

[queengooborg]

I think that using a dictionary instead of an array of strings would have the following benefits:

• Easier to migrate codebase
  • Consumers would only have to change a small bit of code: from if (browser.accepts_flags) to if (browser.accepts.flags) (instead of browser.accepts.includes('flags'))
• Opens the possibility for adding version numbers (mentioned above)
  • This is something that I have been thinking about implementing in the future. The motivation for this is to enforce version number consistency for specific categories for when a feature category was introduced, and I've been thinking about extending it to other categories like webassembly
  • This would also mean that we don't have to release a new major version if we convert the schema to this structure
• Allows for retaining TypeScript documentation
  • If we continue to use a dictionary, we can add TypeScript/schema comments that describe what the property means in better detail

[caugner]

I think that using a dictionary instead of an array of strings would have the following benefits:

Done in a7ede72.

[queengooborg]

Suggested change

	An optional object indicating which additional features the browser supports. Possible properties are:
	An object indicating which additional features the browser supports. Possible properties are: