upgrade testing to swift testing framework

[bwdmr]

Description

id propose to upgrade from xct to swift testing. as part of the overall conformity with upcoming swift versions.
id put in the work aswell.

Additional information

No response

[simonjbeaumont]

Thanks for filing, and thanks for offering to do the work.

Is there something you think would be improved by migrating existing tests to Swift Testing?

My position is that we should be adopting Swift Testing for any new test suites we write, but migrating existing tests from XCTest to Swift Testing buys us little. After the investment, the best outcome is that we haven't regressed the testing in a subtle way.