Change test matching strategy to include all test files

[danielholmes]

What's Changing and Why

I noticed when running tests for core that one was missed:

> yarn test
yarn run v1.22.19
$ cross-env BABEL_ENV=test mocha --require @babel/register test/**/*.js


  Mime
    getType
      ✓ should return undefined if not found
      ✓ should return the correct mime
    getExtension
      ✓ should return undefined if not found
      ✓ should return the correct extension


  4 passing (26ms)

✨  Done in 0.83s.

But there are actually 5 tests. After the change included here:

> yarn test
yarn run v1.22.19
$ cross-env BABEL_ENV=test mocha --require @babel/register --recursive test --extension js


  redirect
    ✓ follows 301 redirect

  Mime
    getType
      ✓ should return undefined if not found
      ✓ should return the correct mime
    getExtension
      ✓ should return undefined if not found
      ✓ should return the correct extension


  5 passing (49ms)

✨  Done in 0.95s.

I also added a test script for the gif plugin and switched the all test scripts to match tests in a less error prone way.

What else might be affected

This is only development side. All tests seem to run fine still.

Tasks

• Add tests
• Update Documentation
• Update jimp.d.ts
• Add SemVer Label

[github-actions]

🚀 PR was released in v0.22.0 🚀