Add UntrimmedImport tests

cabal-testsuite/PackageTests/UntrimmedImport/cabal.out

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+# checking project import with trailing space
+# cabal v2-build
+Error: [Cabal-7090]
+Error parsing project file <ROOT>/trailing-space.project:
+import has whitespace;
+  'https://www.stackage.org/nightly-2024-12-05/cabal.config '
+    imported by: trailing-space.project
+# checking project import with tabs and spaces
+# cabal v2-build
+Error: [Cabal-7090]
+Error parsing project file <ROOT>/tabs-and-spaces.project:
+import has whitespace;
+  'https://www.stackage.org/nightly-2024-12-05/cabal.config		   '
+    imported by: tabs-and-spaces.project

cabal-testsuite/PackageTests/UntrimmedImport/cabal.test.hs

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+import Test.Cabal.Prelude
+
+main = cabalTest . recordMode RecordMarked $ do
+  let log = recordHeader . pure
+
+  log "checking project import with trailing space"
+  trailing <- fails $ cabal' "v2-build" [ "--project-file=trailing-space.project" ]
+  assertOutputContains "import has whitespace" trailing
+  assertOutputContains "'https://www.stackage.org/nightly-2024-12-05/cabal.config '" trailing
+
+  log "checking project import with tabs and spaces"
+  fails $ cabal "v2-build" [ "--project-file=tabs-and-spaces.project" ]

cabal-testsuite/PackageTests/UntrimmedImport/tabs-and-spaces.project

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+optional-packages: .
+import:		https://www.stackage.org/nightly-2024-12-05/cabal.config		   

cabal-testsuite/PackageTests/UntrimmedImport/trailing-space.project

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+optional-packages: .
+import: https://www.stackage.org/nightly-2024-12-05/cabal.config