bug(developer): kmc-package needs to translate backslashes to slashes for cross-platform (`common/test/keyboards/build.sh` fails on Linux)

[ermshiperete]

When I try to compile the test keyboards with common/test/keyboards/build.sh --index on Linux, the build fails with:

...
k_046___deadkey_and_contextex.kmn - info KM05006: baseline/k_046___deadkey_and_contextex.kmn built successfully.
k_047___caps_always_off_initially_on.kmn - info KM05002: Building baseline/k_047___caps_always_off_initially_on.kmn
k_047___caps_always_off_initially_on.kmn - info KM05006: baseline/k_047___caps_always_off_initially_on.kmn built successfully.
k_048___modifier_keys_keep_context.kmn - info KM05002: Building baseline/k_048___modifier_keys_keep_context.kmn
k_048___modifier_keys_keep_context.kmn - info KM05006: baseline/k_048___modifier_keys_keep_context.kmn built successfully.
baseline.kpj - info KM0500B: Project baseline/baseline.kpj built successfully.

caps_lock_layer_3620.kpj - info KM05002: Building caps_lock_layer_3620/caps_lock_layer_3620.kpj
caps_lock_layer_3620.kmn - info KM05002: Building caps_lock_layer_3620/source/caps_lock_layer_3620.kmn
caps_lock_layer_3620.kmn - info KM05006: caps_lock_layer_3620/source/caps_lock_layer_3620.kmn built successfully.
caps_lock_layer_3620.kps - info KM05002: Building caps_lock_layer_3620/source/caps_lock_layer_3620.kps
caps_lock_layer_3620.kps - error KM04008: Keyboard caps_lock_layer_3620 was listed in <Keyboards> but a corresponding .kmx file was not found in <Files>
caps_lock_layer_3620.kps - info KM05007: caps_lock_layer_3620/source/caps_lock_layer_3620.kps failed to build.
caps_lock_layer_3620.kpj - info KM0500C: Project caps_lock_layer_3620/caps_lock_layer_3620.kpj failed to build.
[common/test/keyboards] ## build failed

master branch, commit cb1b995d62194b9a9ccca1df2434785fa7e3aa7b

[ermshiperete]

The reason it fails are the Windows path separators (\) in the .kps and .kpj files.

[mcdurdin]

This is a bug in kmc then, needs resolution before beta.