Import transactions in sequence on signer

[Alenar]

Content

This PR break up in chunk the mithril-signer transactions import process, so the transactions pruning is done more frequently, reducing the number of transactions stored at any given time, reducing the disk footprint.

The chunk size is set to 1500 and is configurable.

Pre-submit checklist

• Branch
  • [x] Tests are provided (if possible)
  • [x] Crates versions are updated (if relevant)
  • [x] 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
• Documentation
  • [ ] Update README file (if relevant)
  • [ ] Update documentation website (if relevant)
  • [ ] Add dev blog post (if relevant)

Issue(s)

Closes #1766

[github-actions[bot]]

Test Results

    4 files  ±0     51 suites  ±0   8m 52s :stopwatch: +12s 1 078 tests +5  1 078 :white_check_mark: +5  0 :zzz: ±0  0 :x: ±0  1 226 runs  +5  1 226 :white_check_mark: +5  0 :zzz: ±0  0 :x: ±0 

Results for commit dfccf4fa. ± Comparison against base commit e4692ff5.

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