This adapts all client code to use the two new libraries and then deletes all unused code (mostly related to the old DB which is isn't anymore).
If a repository supports the new index-v2 format, it will automatically be used allowing subsequent index updates to be applied as diffs. This is still experimental and should be tested once the official F-Droid repo switches on index-v2 support.
This is put up as a Draft. It still includes DO NOT MERGE commits and should not be merged without a proper migration strategy and extensive testing.
Fixes #649 (closed), #860 (closed), #1206 (closed), #1588, #1710 (closed), #1989 (closed), #2080 (closed), #2081 (closed), #2157 (closed), #2322 (closed), #2353 (closed), #2370 (closed), #2412 (closed), #2436 (closed), #2442 (closed), #2443 (closed), #2444 (closed)
Might fix #1971 (closed)