Manifest3 API - compatible version

[w010]

Due to Google dropping support for Manifest v2 - based Chrome extensions, which soon will stop working, the Manifest v3 - compatible updated version is being tested currently. It's not yet published, many low-level things had to be rewritten and it needs some more testing to find issues.

Feel free to install it locally, checkout branch manifest3 and check if it works well for you.

Also - this version finally includes a long waited gamechanging feature - it can switch to Backend directly to the page which was open in Frontend, and in that language.
(for this to work, it tries to find and fetch these uids from frontend's body/html id or class, expects it to be like pid-nn, page-nn, lang-x, or language-y)
That currently works good, in TYPO 11 and up, thanks for the backend routes/deep links.

WIP: it will support also News and custom records on detail view, which will lead directly to edit form. Needs some time to finish that. (it will need similar, additional class in body to work, at least until the js selector and regexp pattern will be configurable)