Fixes#7487.
`KMN_API` defines only import/export/static modifiers for functions, so
it makes no sense to apply it to a typedef. (Previously, I thought it
also included a calling convention, but it doesn't.)
Recently some include files got added to `common/include` which are
referenced by `core/include/keyman`. This change adds the necessary
code to install them in the same directory as the other include files.
Fixes#7490.
Adds infrastructure required to support caps lock control on keyboard
activation per #5822.
Keyboardprocessor implementation is currently a stub, and engines will
need corresponding updates to support the new API.
