ci: improve test-mithril-client-wasm job debugging by uploading logs as artifacts

[dlachaume]

Content

This PR uploads Chrome console and driver logs, and Firefox driver logs, when WASM headless tests fail in the test-mithril-client-wasm step of the Mithril Client multi-platform test workflow.
Note: Firefox WebDriver does not currently support retrieving browser console logs via get_log('browser').

Pre-submit checklist

• Branch
  • Tests are provided (if possible)
  • Crates versions are updated (if relevant)
  • CHANGELOG file is updated (if relevant)
  • Commit sequence broadly makes sense
  • Key commits have useful messages
• PR
  • All check jobs of the CI have succeeded
  • Self-reviewed the diff
  • Useful pull request description
  • Reviewer requested
• Documentation
  • Update README file (if relevant)
  • Update documentation website (if relevant)
  • Add dev blog post (if relevant)
  • Add ADR blog post or Dev ADR entry (if relevant)
  • No new TODOs introduced

Issue(s)

Closes #2579

[github-actions]

Test Results

    3 files  ±0    102 suites  ±0   16m 4s ⏱️ -32s
2 048 tests ±0  2 048 ✅ ±0  0 💤 ±0  0 ❌ ±0 
4 229 runs  ±0  4 229 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit e286e56. ± Comparison against base commit 63bc902.

[jpraynaud]

LGTM 👍

[turmelclem]

LGTM