Description of the change

This PR opinionatedly declares eslint as the default linter for rollbar-react, and prettier the default formatter, as is in Olympus.

The same formatting configuration as Olympus has been used and the build CI has been rewritten with updated actions, caching and a linting step that runs eslint and prettier.

Eslint configuration for each example has been made its own root eslint configuration to avoid grabbing the library's eslint config which defines plugins incompatible with apps.

Eslint ignore file has been added to avoid eslint linting the dist directory, and others.

ESLint warnings and errors have been fixed across all examples and library sources.

Prettier formatting has been applied across all examples and library sources.

I recommend going over the changes using the Unified diff view + hiding whitespaces.

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