Force preference on the user specified action on commandline.
This allows upgrading packages which would otherwise be kept back
due to partial update preferring to keep top level dependency on
the installed version.

fixes #7531

fixes #10721

It makes sense to not prioritize requirers anymore. It was
originally intended to select early packages with multiple
constraints seen. However, more important are the constraints
that actually limit the choise.

fixes #10843

Correctly trigger install_ifs for provided names also. And fix the
construction of error messages concerning such install_if packages.

ref #10843

This reverts most of 0dcbd933 which allowed automatic selection
of package with a "virtual provides" having only one provider.
While convenient, it creates problems if multiple versions of the
same package exist, or if in future other providers would be added
to one of the repositories. This restore the original behaviour,
and improve the error message to tell the user to mention one of
the providers explicitly.

fixes #10810

The original intent was to choose packages to which there is most
dependencies. However, since the code has evolved this is has been
mostly obsolete. And in fact now interferes with the provides and
provides priority mechanism. Remove this as obsolete.

Fixes #10742

makes apk_verbosity non-global

fixes #10682

ref #10682

This greatly helps with memory management on applications that
may want to daemonize and open/close database several times.

Also the lifetime and "owner" of memory for all data is now
explicitly bound to owning struct apk_database, which might
be helpful when writing language bindings. As side effect, the
interned "atoms" are unique only within what apk_database, so
comparing packages from different apk_database may not work
as expected.

Fixes #10697

Notably this fixes occasional issues when doing upgrade with multiple
versions of same packages. Without this the upgrade flag is not always
propagated properly down the dependency chain.

remove also redundant pkg_selectable check in repair mode.

This unloads --force as several of the things are really not wanted
together. E.g. --force-refresh is a lot different from --force-broken-world
and doing --force to get the other might introduce unwanted behaviour.

--force is still kept for backwards compatibility and it enables
most things --force was used for.

In discovery phase, there was logic to not process packages
multiple times. However, that logic failed to account the package's
depth and install_if state for the name being processed. This
caused install_if processing failure in certain topologies of the
dependency graph. Adds also a test case that should catch this
issue reliably.

This ensures a swap is emitted when replacing a virtual with
apk add.

By introducing a new package metadata field, `provider_priority`
(index letter `k`), we can specify default packages to satisfy a
virtual.

If a user wishes to select an alternative provider for the virtual,
a changeset swapping the default provider for the selected provider
will be generated by the dependency resolver.

this fixes package selection when a 'real' package exists, but would
need to be provided by another package with 'virtual provides'.

In current package database this can happen with postgresql which is
also provided by postgresql-bdr. Normally postgresql would be satisfied
by postgresql, but if any package depends on postgresql-bdr and there's
no versioned dependency on postgresql this will help apk figure out
that postgresql-bdr should be used.

solver: don't clobber package swaps in cases where an installed package is being replaced by a provider

The virtual package provider still needs to be explicitly
given on command line.

trigger it only if apk-tools can be upgrade, add test cases

this makes 'lbu diff' and aaudit diffs nice when a world
dependency is added or removed. sorting also makes the ordering
more deterministic as the world targets constraints are always
applied in the same order. test suite updated accordingly.

when removing large sets of packets, the ordering of removal
was not quaranteed to honor dependencies. this fixes the removal
order to be in reverse dependency order as far as possible.

This makes sure any conflicted packages will be removed first.
Useful if we know there are conflicting files, and want to avoid
adding potentially harmful replaces line. Add a test case for
this too.

allow packages in the cache's installed to be selected for installation
by the solver. add test case for the issue.