Relax check file match with stack trace

[som-snytt]

A handful of tests under neg-macros include a stack trace in the check file, which makes them sensitive to irrelevant changes in distant source code.

This commit conservatively ignores line numbers in stack trace output when doing line text comparisons of test output.

A future improvement would be for suppressAllOutput to be a filter that can suppress output or normalize it on a per-need basis.

The test group name is corrected to negMacros.

As shown at 3cff3be

// //> using options -language:experimental.modularity -source future

did not previously turn off the options, as it did for scala-cli. It's not immediately obvious whether it's a bug that the test requires the objects (which are removed for other tests in that commit).

Now, //> must be at the beginning of the line. (There may be other ways the test syntax could be aligned with CLI directives.)

[SolalPirelli]

If the specific goal is macro-related code, should this be enabled only for those? IMHO ignoring all line numbers is risky and might hide unrelated bugs...

[som-snytt]

In my experience, testing stack traces by default is noise. The tweak only relaxes the source line, which changes with arbitrary edits.

If I want to test a stack trace or positions, I would do that with a predicate that explains what property of the stack elements is being enforced.

The current situation is poor isolation of tests.

By contrast, a tweak to tree positions will annoyingly but helpfully require updates to tests.

(Edit: similarly for the inlined positions shown for errors, which are a feature.)

I think the fix for the directive in tests may have got in already. (Edit: no, that's a different fix!)