Add step for Behat faildump storing as GHA artifact.

[kabalin]

Add GHA step to store Behat faildump as workflow artifact, so it can be inspected.

This step will be run only if Behat step failed (see if statement). It also configured not to produce warning if files are not found (the cause of Behat error might be not the actual test scenario). Name is derived from the job matrix, it needs to be unique per job when matrix is used (artifact upload will fail on name conflict if more than 1 job will fail on Behat)

Demo (simplified for speed):

• Failed job: https://github.com/kabalin/moodle-format_flexsections/actions/runs/8307608604
• Succeeded job (no artifacts): https://github.com/kabalin/moodle-format_flexsections/actions/runs/8307723810

More info on upload artifact: https://github.com/actions/upload-artifact

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.04%. Comparing base (7b22048) to head (5e7efd1).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff            @@
##               main     #291   +/-   ##
=========================================
  Coverage     88.04%   88.04%           
  Complexity      731      731           
=========================================
  Files            75       75           
  Lines          2234     2234           
=========================================
  Hits           1967     1967           
  Misses          267      267           

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[stronk7]

LGTM! 😛

[kabalin]

BTW, kudos also go to @marinaglancy who suggested the similar idea for our internal GitLab jobs 🎉