Add property to disable the default set of command-line options for testing

[Youssef1313]

At least for MTP, we need that in microsoft/testfx.

See microsoft/testfx#6140 for context.

Basically, we run official builds with Arcade, but PRs/public builds with dotnet test, and we want to unify everything to use TestingPlatformCommandLineArguments.

However, for dotnet test we will need to add --results-directory ourselves to TestingPlatformCommandLineArguments, but that then will be picked up by Arcade resulting in duplicate --results-directory which is an error.

The ask is to modify (at least) Microsoft.Testing.Platform.targets to conditionally include --results-directory, --report-trx, --report-trx-filename. These will be added by default. Repos that wish to opt-out from that behavior can specify <ArcadeDisableMTPCommandLineOptions>true</ArcadeDisableMTPCommandLineOptions>