Include doxyfile templates in OSAL

[jphickey]

Is your feature request related to a problem? Please describe.
Currently the OSAL API is marked up with doxygen, but the required Doxyfile config file/template exists in the CFE repo, not in the OSAL repo.

Describe the solution you'd like
The Doxyfile and other support/config files for the OSAL guide should exist in this repository, in the docs directory, so OSAL documentation can be generated on its own without CFE.

Additional context
OSAL is supposed to be a standalone product, but currently only CFE users can generate OSAL documentation. It also makes management harder having certain config files in a separate repo.

Requester Info
Joseph Hickey, Vantage Systems, Inc.

[jphickey]

Discovered this was already noted in #913