Removed JSON-js submodule and integrated the modified json3 directly

[matux]

Description of the change

This PR removes the only submodule in the workspace, a forked version of JSON-js @ https://github.com/rollbar/JSON-js and integrates it directly into the project.

The last time the code in the fork was changed is 2015, and given we only seem to use json3, it does not seem like we're using any of the modified code.

Note

This was mainly done with the aim of making the move to a monorepo easier.

Type of change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Maintenance
• New release

Checklists

Development

• Lint rules pass locally
• The code changed/added as part of this pull request has been covered with tests
• All tests related to the changed code pass in development

Code review

• This pull request has a descriptive title and information useful to a reviewer. There may be a screenshot or screencast attached
• "Ready for review" label attached to the PR and reviewers assigned
• Issue from task tracker has a link to this pull request
• Changes have been reviewed by at least one other engineer