Add initial test metadata using the FMF format
This adds an initial set of test metadata using the Flexible Metadata
Format for experimenting. This should allow us to more easily execute
relevant test coverage for all selinux-related components. Example:
fmf --key test --filter 'tags:Tier1'
fmf --key test --filter 'component:libselinux'
fmf --key test --filter 'component:libselinux | tags:Tier1'
See https://github.com/psss/fmf for more details about the FMF format.