Migrate workspace tests

[thePianoKid]

I made two big changes in this PR:

1. Migrate from XCTest to Swift Testing

• func test<test name> -> @Test func <test name>
• XCTAssertNoDiagnostics -> expectNoDiagnostics
• PackageGraphTesterXCTest -> try PackageGraphTester
• Change implementation of checkPackageGraphFailure:

Before:

await workspace.checkPackageGraphFailure(roots: ["Foo", "Nested/Foo"]) { diagnostics in
            testDiagnostics(diagnostics) { result in

After:

try await workspace.checkPackageGraphFailure(roots: ["Foo", "Nested/Foo"]) { diagnostics in
            try expectDiagnostics(diagnostics) { result in

• XCTAssertMatch -> #expect(<expected>.matches(<actual>))

This commit shows a clean diff of what was refactored.

2. Parameterized Tests

I recently wrote these tests. In these tests, the same logic is being applied to different inputs. They should be parameterized. I make this refactor in this commit.

Blocked by #9966