upgrade to Manifest V3

[marcustyphoon]

Description

Updates the manifest file to MV3, as will soon be required for Chrome installation.

As of #178, I don't believe any code changes will be required. oops, nope, firefox

Testing steps

Extremely basic testing performed in Chrome 125; I have not tested this in Firefox, Firefox for Android, or Chrome ~88.

[marcustyphoon]

• add id to gecko manifest field
• add ui to call browser.permissions.request if origin permissions are unavailable

We could also consider setting the minimum Firefox version to at least 127, in which users will (it seems) continue to have the extension work in the background without manually granting origin permissions. And, after all, why not?

There may be other MV3 improvements in 128, as well, which could be a better target (it's going to be ESR, too). The MV2 version will keep working on Firefox and I assume there's a decent chance we don't push a functionality/feature commit on this one for a while, so not updating Firefox users for a bit could be fine.

This does not make the second item pointless, as mentioned in the link, but it makes it less important.

[marcustyphoon]

The MV2 version will keep working on Firefox and I assume there's a decent chance we don't push a functionality/feature commit on this one for a while, so not updating Firefox users for a bit could be fine.

Only sort of true. I have discovered that if your latest version does not run on the user's Firefox, your extension will not appear in AMO's search for that user, and if the user navigates manually to the extension page on AMO, the install button is greyed out. So one should generally not deploy a version with a very strict Firefox requirement.

[AprilSylph]

I don't think we need the permissions banner on the "options" page, since it doesn't handle the application of palettes, just the managing of them. If the user can find the options page but not the action popup, they wouldn't be able to apply palettes even if the host permission is already granted.

[AprilSylph]

Tested and working on Firefox 130.0b6 (64-bit).