Upgrade to manifest v3

[sbrudz]

• Upgrade JustNotSorry to use v3 of the web extension manifest
• Remove the custom user installation Google Analytics event, allowing us to reduce the scope of the permissions needed by the extension. We already get install events reported to google analytics via the Chrome Web Store, so we shouldn't miss this data.
• Remove the declarativeContent permission because the content_scripts in the manifest already provide permissions for these sites.

Fixes https://github.com/defmethodinc/just-not-sorry/issues/159

Note that this PR is a repeat of #160, which was merged into the beta branch for testing. I had to clean up the git history on the branch so that semantic release didn't think old features/fixes were getting released again.

[github-actions[bot]]

:tada: This PR is included in version 2.4.0 :tada:

The release is available on GitHub release

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