Implement v2-outdated command for cabal-install

This commit updates the outdated command to the new v2 architecture:

- Transform the old `outdated` command into a new v2-style command `v2-outdated`
- Support three modes of operation:
  - Check for outdated dependencies in v1-style freeze file
  - Check for outdated dependencies in project context (cabal.project & cabal.project.freeze)
  - Check for outdated dependencies in local packages

Since the `cabal outdated` command now supports the v2-architecture, you
can request to run the `v2-outdated` command on any target.

I also introduced the `resolveTargetsFromLocalPackages` which resolves
which local packages targets refer to without having to run the solver.
This will be useful for `cabal check` as well.

A change in behaviour from before is that the package description is
flattened, so all bounds will be warned about rather than those in
conditional branches being ignored.

Fixes #8283

Author: mpickering

Cabal-syntax/src/Distribution/Utils/Generic.hs

@@ -56,6 +56,7 @@ module Distribution.Utils.Generic
   , listUnion
   , listUnionRight
   , ordNub
+  , sortNub
   , ordNubBy
   , ordNubRight
   , safeHead
@@ -385,6 +386,10 @@ ordNubRight = fst . foldr go ([], Set.empty)
         then p
         else (x : l, Set.insert x s)
 
+-- | Sort and nub a list
+sortNub :: Ord a => [a] -> [a]
+sortNub = Set.toList . Set.fromList
+
 -- | A right-biased version of 'listUnion'.
 --
 -- Example:

Cabal/src/Distribution/Simple/Utils.hs

@@ -185,6 +185,7 @@ module Distribution.Simple.Utils
   , listUnion
   , listUnionRight
   , ordNub
+  , sortNub
   , ordNubBy
   , ordNubRight
   , safeHead

cabal-install-solver/src/Distribution/Solver/Types/ProjectConfigPath.hs

@@ -38,7 +38,7 @@ import qualified System.FilePath.Posix as Posix
 import qualified System.FilePath.Windows as Windows
 import qualified Data.List.NonEmpty as NE
 import Distribution.Solver.Modular.Version (VR)
-import Distribution.Pretty (prettyShow)
+import Distribution.Pretty (prettyShow, Pretty(..))
 import Distribution.Utils.String (trim)
 import Text.PrettyPrint
 import Distribution.Simple.Utils (ordNub)
@@ -58,6 +58,9 @@ import Distribution.System (OS(Windows), buildOS)
 newtype ProjectConfigPath = ProjectConfigPath (NonEmpty FilePath)
     deriving (Eq, Show, Generic)
 
+instance Pretty ProjectConfigPath where
+  pretty = docProjectConfigPath
+
 -- | Sorts URIs after local file paths and longer file paths after shorter ones
 -- as measured by the number of path segments. If still equal, then sorting is
 -- lexical.