This essentially makes -z/--ignore-project appear in all v2-commands

Resolve #6804: v2-update reports new index-state

Fix #6805: More compatible rpmvercmp behavior

Regex list

For example:

    Downloading the latest package list from hackage.haskell.org
    Updated package list of hackage.haskell.org to index-state 2020-05-15T09:13:06Z
    To revert to previous state run:
        cabal v2-update 'hackage.haskell.org,2020-05-10T18:58:02Z'

Or

    Package list of hackage.haskell.org is up to date at index-state 2020-05-15T09:13:06Z

To get exact match you can

    % cabal list ^QuickCheck$ -I
    * QuickCheck
        Synopsis: Automatic testing of Haskell programs
    ...

But not the prefix/suffix/regexp matching is in your power for
searching. e.g.

    % cabal list ^Cabal
    * Cabal
        Synopsis: A framework for packaging Haskell software
    ...
    * cabal-install
        Synopsis: The command-line interface for Cabal and Hackage.
    ...
    and many others

Resolve #6409: Add public multilib test(s)

    % cabal list transformers --installed
    * transformers
        Synopsis: Concrete functor and monad transformers
        Default available version: 0.5.6.2
        Installed versions: 0.5.6.2
        License:  BSD3

    % cabal list transformers --installed -w ghc-8.10.1
    * transformers
        Synopsis: Concrete functor and monad transformers
        Default available version: 0.5.6.2
        Installed versions: 0.5.6.2
        License:  BSD3

    % cabal list transformers --installed -w ghc-7.6.3
    No matches found.

    % cabal list transformers --installed -w ghc-7.8.4
    * transformers
        Synopsis: Concrete functor and monad transformers
        Default available version: 0.5.6.2
        Installed versions: 0.3.0.0
        License:  BSD3

Also add a test for current behaviour
of https://github.com/haskell/cabal/issues/6083

And variant with mixin, for https://github.com/haskell/cabal/issues/6281

The tests are disable for GHC older than 8.8
Should they work?

Add NonEmptySet and use it in Dependency

Described Mixin

Remove Text type-class

Parse Globs with parsec

Refactor FieldGrammar / Described

Move Described functionality there, out of Cabal the library.
Similarly cabal-install doesn't contain Described instances,
they are only in tests.

Add more weeder roots

This makes type-signatures awful, but using _ one can infer them.
Parsing performance doesn't seem to be affected.

Also move Newtypes to Distribution.FieldGrammar.Newtypes as that is
more correct place.

Create Cabal-tree-diff package

Move Cabal instances from cabal-install TreeDiffInstances into it.
Remove defaultToExprViaShow to get better diffs and dumps

Also rename Cabal-QuickCheck (proper case), and add GenericArbitrary
module there.

Remove Text WorldPkgInfo

Use Pretty/Parsec in Init (remote Text Category instance)

Resolve #6589: Remove -any and -none syntax

Change BuildReports parse/pretty to use FieldGrammar framework

More described