Feature/enhancement of hoverinig buttons

[haarsh157]

Fixes #2823, #2905

Changes:

1. Changed hovering color to p5jsActivePink.
2. Added new yellow color p5ContrastYellow and changed the button hovering color in the contrast theme.

I have verified that this pull request:

• [x] has no linting errors (npm run lint)
• [x] has no test errors (npm run test)
• [x] is from a uniquely-named feature branch and is up to date with the develop branch.
• [x] is descriptively named and links to an issue number, i.e. Fixes #2823

[release-com[bot]]

Release Environments

This Environment is provided by Release, learn more! To see the status of the Environment click on Environment Status below.

• p5.js-web-editor
  • app-teded7a.release.editor.p5js.org/
  • preview-teded7a.release.editor.p5js.org/

:wrench:Environment Status : https://app.release.com/public/Processing%20Foundation/env-3b7ecc2eba