testsuite: optional limiting of coverage dumps

[JordanYates]

Add an option that excludes generation of a given path of .gcda files when running coverage testing. This can be useful when running testing coverage on downstream repos, which would otherwise result in large .gcda files for paths we don't care about filling up the disk.

The issue triggering this PR was huge portions of coverage dumps for my downstream repo being just MbedTLS data, which was ignored at the next processing step due to --coverage-basedir. The dumped data ended up being so large that something between QEMU and handler.log was having trouble actually saving it all, leading to test failures due to "GCOV_COVERAGE_DUMP_END" not being found in the file.

[nashif]

looks reasonable.
btw, been looking into using semihosting instead of console dumps, see #94079

[Copilot]

Pull Request Overview

This PR adds configuration options to limit coverage dump generation by allowing users to filter which files are included in .gcda files during coverage testing. This addresses issues where coverage dumps become excessively large due to unwanted library data (like MbedTLS) causing disk space issues and test failures.

• Added a new configuration option COVERAGE_DUMP_PATH_EXCLUSIVE for path-based filtering
• Restructured Kconfig to group coverage-related options under a conditional block
• Removed redundant depends on COVERAGE_GCOV clauses

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[JordanYates]

Updated the implementation to instead specify a single exclude pattern. It ended up being much harder than I originally realised to construct a pattern that captured only the files I wanted.
Since the only real problem was the MbedTLS files, a single exclude path does the job fine.
And also resolves the naming concerns.

[nashif]

need rebase

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[tristan-google]

This change appears to be causing issues in our code coverage builds since fnmatch is not supported by all the libc options. Picolibc and most host-provided libraries have it, minimal libc does not, and I don't think newlib does either (less sure about that one, but I didn't see it in its docs)

I think we need to add some depends on clauses to this Kconfig option and guard the references to fnmatch and fnmatch.h in coverage.c

[tristan-google]

Please take a look at #97148 as possible solution