Add `Makefiles` to facilitate the update of `www` and `www-test` dependencies

[dlachaume]

Content

This PR includes two new Makefile for www and www-test. It facilitates the update of the projects dependencies.

From mithril-client-wasm directory, run: make upgrade-www-deps

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
• Documentation
  • [ ] Update README file (if relevant)
  • [ ] Update documentation website (if relevant)
  • [ ] Add dev blog post (if relevant)

[github-actions[bot]]

Test Results

    3 files  ±0     43 suites  ±0   8m 28s :stopwatch: -6s 1 013 tests ±0  1 013 :white_check_mark: ±0  0 :zzz: ±0  0 :x: ±0  1 111 runs  ±0  1 111 :white_check_mark: ±0  0 :zzz: ±0  0 :x: ±0 

Results for commit 03d70386. ± Comparison against base commit 9bf5b986.

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