Increase common coverage and coverage of individual modules

[shanshin]

It is necessary to configure Kover in such a way that it is possible to verify the coverage of individual modules.
The main problem is that many modules do not have tests and are being tested by other modules.

After configuring Kover, we need to consider the uncovered sections of the code and figure out how to significantly increase the percentage of coverage.
If the coverage is greatly increased by writing small tests, then such tests must be written. Otherwise, we need to create a separate task for analyzing and increasing coverage

[sandwwraith]

this + migrate on a new Kover version

[shanshin]

this + migrate on a new Kover version

#2624 :)

[sandwwraith]

By migrating I mean 'Make use of all new features, including merged reports'. But I suppose it is now a part of this ticket