Add code coverage checks and badges

[frankhinek]

Note: Copied over from PR #97

This PR proposes the following changes:

Tests

• Add c8 to the six existing packages.
  • Consistent use of .c8rc.json across all packages.
• Add Codecov to the CI GitHub Action.
  • Codecov configured to NOT block PRs if configured coverage thresholds fail to be met. We can consider enforcing this more strictly in the future once the overall lib's test coverage improves.
  • Compares the prior main branch to each PR to see if code coverage decreased by more than 5%
  • Expects new code introduced by a PR to be covered by tests.
  • Code coverage report is printed after every test run.
• CONTRIBUTING.md updated to reflect test coverage expectations.
• Simplifies test:node NPM script in package.json using .mocharc.json config.

Security

• Adds a security-audit job to the CI GitHub Action to confirm there are no vulnerabilities introduced in future PRs.
• Apply override for socket.io-parser at top-level to ensure dev dependency is always overridden.

Docs

• Updates README badge that was previously broken:
  

Dev Environment

• Test All - Node VScode launch script added to the Web5 JS workspace configuration.
• Consistent use and versions of dev dependencies across all projects (e.g., chai, mocha, sinon)

[frankhinek]

@diehuxx in chatting with @mistermoe and @csuwildcat we'd like to include code coverage but to put in the CONTRIBUTOR.md file rather than at the top of the README badges ...but great to check coverage on every PR.

By highlighting in CONTRIBUTING we make it clear there's an expectation of tests and every PR will have an updated state reviewers can easily glance at.

Something like this:

I'm not sure if istanbul-badges-readme can do this but worth investing and perhaps seeing if we can find something that can.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (main@131564a). Click here to learn what that means.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #99   +/-   ##
=======================================
  Coverage        ?   65.50%           
=======================================
  Files           ?       31           
  Lines           ?     3383           
  Branches        ?      195           
=======================================
  Hits            ?     2216           
  Misses          ?     1165           
  Partials        ?        2           

Components	Coverage Δ
crypto	0.00% <0.00%> (?)
dids	48.61% <0.00%> (?)
web5	81.18% <0.00%> (?)
web5-agent	0.00% <0.00%> (?)
web5-proxy-agent	0.00% <0.00%> (?)
web5-user-agent	79.10% <0.00%> (?)

[mistermoe]

this is awesome @frankhinek and @diehuxx