[MTP dotnet test]: Allow specifying project, solution, directory, or test modules as positional argument

[Youssef1313]

Manual backport of #52449 to 10.0.3xx

Closes #52636

[Copilot]

Pull request overview

Backports behavior to the Microsoft.Testing.Platform (MTP) dotnet test command so a project, solution/solution filter, directory, or test modules can be provided as a positional argument (similar to prior VSTest behavior), while still keeping validation for ambiguous/incorrect usage.

Changes:

• Adds parsing of the first unmatched token as a positional “path/test-modules” input and forwards remaining unmatched tokens to the test application.
• Updates mutual-exclusion/validation logic to work off computed PathOptions (including the new TestModules field).
• Expands/adjusts tests to cover positional .slnf and to ensure helpful validation errors still appear for non-first path-like tokens.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
test/dotnet.Tests/CommandTests/Test/TestCommandValidationTests.cs	Updates validation tests to keep path-like tokens from being the first unmatched token.
test/dotnet.Tests/CommandTests/Test/GivenDotnetTestBuildsAndRunsTestsWithDifferentOptions.cs	Adds test coverage for solution filter (.slnf) as the first positional token.
src/Cli/dotnet/Commands/Test/MTP/ValidationUtility.cs	Refactors option mutual-exclusion/irrelevant-option validation to use PathOptions.TestModules.
src/Cli/dotnet/Commands/Test/MTP/TestModulesFilterHandler.cs	Adjusts handler signature to accept test-modules value from computed build/path options.
src/Cli/dotnet/Commands/Test/MTP/TestApplication.cs	Switches forwarded args from UnmatchedTokens to TestApplicationArguments.
src/Cli/dotnet/Commands/Test/MTP/Options.cs	Extends PathOptions to include TestModules and renames forwarded-args list in BuildOptions.
src/Cli/dotnet/Commands/Test/MTP/MicrosoftTestingPlatformTestCommand.cs	Uses computed build options earlier and routes into test-modules mode based on PathOptions.TestModules.
src/Cli/dotnet/Commands/Test/MTP/MSBuildUtility.cs	Implements positional-argument extraction and updates build option construction accordingly.

[Evangelink]

Review Summary

This is a manual backport of #52449 to release/10.0.3xx. The adaptation to the branch's command definition API looks correct in most places, but there are a few issues:

High severity

• Directory positional argument is misclassified as positionalTestModules instead of positionalProjectOrSolution, which will cause runtime failures when users pass a directory as a positional argument (the test-modules glob matcher won't find anything and will produce a confusing "no test modules found" error). This bug is also present in the original PR on main.
• Missing parentheses in the ||/&& condition — works by accident due to precedence but inconsistent and fragile.

Medium severity

• Dead variable filterModeEnabled left behind in MicrosoftTestingPlatformTestCommand.cs.
• Missing test coverage for .csproj, .sln, .slnx, directory, and .dll/.exe as positional arguments, and for the option+positional conflict error.

Low severity

• Extra blank line between methods in MSBuildUtility.cs.