Migrate to manifest v3

[jupenur]

Resolves #58.

[jupenur]

This is targeting the #213 branch, that's why you don't see any tests running here. Review and merge #213 first and GitHub will automatically retarget this to main, then the tests should run.

[jupenur]

Rebased

[lsd-cat]

I wonder what's your opinion on keeping the cache in or our the persistent storage? I don't know how often the bg page will actually be terminated, but my impression would be that the cache would lose a lot of utility this way

[jupenur]

The default timeout is only 30 seconds, so I agree we should probably persist the origin cache. Looking into it now.

[jupenur]

OriginState objects are now persisted per session, matching the pre-MV3 behavior. I decided not to explicitly persist nonOrigins because the in-memory set is already populated via a simple storage lookup here:

webcat/extension/src/webcat/db.ts

Lines 72 to 79 in e6dd261

	// 3. Storage lookup
	const stored = await this.enrollments.get(fqdn);
	if (stored) {
	return new Uint8Array(stored);
	} else {
	this.nonOrigins.add(CacheKey(fqdn, cachePartition));
	return new Uint8Array();
	}

[jupenur]

There was some refactoring involved in making the OriginState classes compatible with session storage. Namely, OriginStateHolder is now gone, and there's only one mutable OriginState class instead; the LRUCache API is now asynchronous (and for consistency so is LRUSet) and subclassed into PersistentLRUCache; and the OriginState class implements a toPOJO method that returns a plain JavaScript object that's compatible with the storage API.

[lsd-cat]

This is great, thank you! I've spent some time trying to figure out the implications of using the storage, especially for risks of race conditions (not necessarily security-sensitive, but still). I'm gonna take some more to brainstorm and test more to see if I can spot and test concrete cases