refactor(developer): add kps-file-reader and kps-file-writer

[mcdurdin]

Relates to kmc-copy project.

Moves the .kps file reader out of kmc-package and adds corresponding kps file writer unit in developer-utils. Also moves related test and error message definition.

@keymanapp-test-bot skip

[keymanapp-test-bot[bot]]

User Test Results

Test specification and instructions

User tests are not required

Test Artifacts

• Developer
  • Keyman Developer
  • Compiler Regression Tests
  • kmcomp.zip
• Keyboards
  • Test Keyboards

[keyman-server]

Changes in this pull request will be available for download in Keyman version 18.0.131-alpha