Remove pending certificate from explorer

[Alenar]

Content

This PR include remove the Pending Certificate component from the explorer.

To fill part of the empty place left by it the Epoch Settings component layout is changed to be horizontal, plus this supplementary horizontal space allow to show its two buttons ("signer registrations" & "in/out registrations") instead of stacking them. Here is how it looks:

This PR also:

• Adapt the Epoch Settings component to the new naming scheme defined in #1966 (with a fallback for aggregator that have still be updated).
• Change the way that data are fetched: data are updated when reloading or changing the selected aggregator regardless of the state of the pause/resume button.

Pre-submit checklist

• Branch
  • [ ] Tests are provided (if possible)
  • [ ] Crates versions are updated (if relevant)
  • [ ] CHANGELOG file is updated (if relevant)
  • [x] Commit sequence broadly makes sense
  • [x] Key commits have useful messages
• PR
  • [x] No clippy warnings in the CI
  • [x] Self-reviewed the diff
  • [x] Useful pull request description
  • [x] Reviewer requested

Issue(s)

Closes #2025, closes #1966

[github-actions[bot]]

Test Results

    4 files  ±0     51 suites  ±0   10m 30s ⏱️ ±0s 1 415 tests ±0  1 415 ✅ ±0  0 💤 ±0  0 ❌ ±0  1 626 runs  ±0  1 626 ✅ ±0  0 💤 ±0  0 ❌ ±0 

Results for commit 825e6ab7. ± Comparison against base commit 678e6e9c.

:recycle: This comment has been updated with latest results.