Remove .eslintrc.js and use consolidated "eslint-config-yscope"; refactor MenuBar and add settings and help modals.

[junhaoliao]

References

Previous ESLint configurations have been consolidated into eslint-config-yscope together with new rules.

Description

1. Remove .eslintrc.js.
2. Add consolidated "eslint-config-yscope" into devDependencies and use it.
3. Refactor MenuBar and add settings and help modals.

Validation performed

1. Ran ESLint on VCS changed files and verified no errors or warnings except for the TODO comments and the unused React variable warning:

   'React' is defined but never used no-unused-vars
   

   The unused React variable can be removed once the we configure babel-loader to use "automatic" transform runtime as documented at https://legacy.reactjs.org/blog/2020/09/22/introducing-the-new-jsx-transform.html .
2. Configured eventsPerPage and theme in the settings modal and confirmed the new settings work.
3. Opened the Help modal which correctly displayed the shortcuts help table.

[junhaoliao]

Closing this PR as the changes were made to a deprecated version of the log viewer. The functionality / improvements introduced here has already been implemented in the new version of the log viewer, which replaced the codebase in PR #101.