test(developer): kmcmplib compiler unit tests 4

[markcsinclair]

Google Test based unit tests for Compiler.cpp

Continues PR #11990

@keymanapp-test-bot skip

[keymanapp-test-bot[bot]]

User Test Results

Test specification and instructions

User tests are not required

[markcsinclair]

Ready to review.

Some tidying up, with additional initialiser funtions, of gtest-compiler-test.cpp. Most new test cases address use(), reset() and virtual keys. There are some problems with spacing of virtual keys (see #12307), and four commented out test cases partially address these - more will be added when a fix is developed.

[keyman-server]

Changes in this pull request will be available for download in Keyman version 18.0.133-alpha