…cessing#1497)

Implements @skyash-dev's solution from the p5.js repository:

- add a github action to generate the image in contributors-png.yml
  - add utils/contributors-png.js to use node & canvas to make an image
  - use processing-bot to generate a pull request with the new updated
    image when the all contributors file is changed
  - action only applies to processing/processing4 repo's main branch
- add contributors.png file with current list of contributors (generated
  during testing)
- make contributors.png visible in the README in the contributors section

and use verbose output so that during release actions, someone can
get a little info to debug the issue even if they don't have a mac.

this ended up being implemented in the gradle build file instead of
the release.yml file, because the Build with Gradle step (which is
`./gradlew packageDistributionForCurrentOS`) includes both
signing and notarization. to stop the build early if the app signing
failed, the intervening check had to be inserted into the normal
build process.

…essing#1510)

fixes issue with Mac app notarization failure by signing the whole app again
after fileAssocations are made. previously, release builds were failing because
the .icns files for .pde, .pdex, and .pdez were added to the .app file after
signing.

* Add ShapeTests for Processing4

* Rename ShapeTests to PGraphicsTests, move to core package, merge tests

Expanded explanation of Gradle plugin's role (sentence was incomplete).

Co-authored-by: Elise Ferguson <eliseferguson@Elises-MacBook-Air.local>