Add --project-dir flag

cabal-install/src/Distribution/Client/CmdClean.hs

cabal-install/src/Distribution/Client/CmdOutdated.hs

cabal-install/src/Distribution/Client/Config.hs

cabal-install/src/Distribution/Client/DistDirLayout.hs

cabal-install/src/Distribution/Client/ProjectConfig.hs

...l-install/src/Distribution/Client/ProjectConfig/Legacy.hs

cabal-install/src/Distribution/Client/ProjectConfig/Types.hs

cabal-install/src/Distribution/Client/ProjectFlags.hs

...l-install/src/Distribution/Client/ProjectOrchestration.hs

cabal-install/tests/IntegrationTests2.hs

...-install/tests/UnitTests/Distribution/Client/Configure.hs

...tall/tests/UnitTests/Distribution/Client/ProjectConfig.hs

cabal-install/tests/fixtures/project-root/cabal.project

...l-install/tests/fixtures/project-root/cabal.project.other

cabal-install/tests/fixtures/project-root/lib/.gitkeep

cabal-install/tests/fixtures/project-root/nix/cabal.project

...stall/tests/fixtures/project-root/nix/cabal.project.other

...testsuite/PackageTests/ConditionalAndImport/cabal.test.hs

...testsuite/PackageTests/Outdated/outdated-project-file.out

cabal-testsuite/PackageTests/ProjectDir/app/App.hs