Add root projects to use for development with CLion

The additional files are useful when generating the CLion project
definition (as documented in
https://android.googlesource.com/platform/build/soong/+/master/docs/clion.md)
to have a single view of the project.

Test: generate CLion project files and open the projects
Change-Id: I10d0a05a1ad827e253c46768f41ac87fa6d00fc9
2 files changed