Modify how CMake handles required components of a CPS transitive
dependency to not pass them as COMPONENTS if a CMake-script package is
found as the resolved dependency. This is necessary as many CMake-script
package description files do not treat component requests as target
requests (which, in CPS-land, they effectively are), but do implement
logic to mark themselves 'not found' if requested components are
missing. As a result, passing in the required targets as required
components is likely to cause the dependency to be spuriously not found
if it is only available via a CMake-script package configuration file.
Fix this by introducing a new 'required targets' concept, and by passing
CPS component requirements as both required targets and optional
components. The latter serves as a hint for packages that might provide
only a subset of themselves. The former is used to post-validate a
CMake-script package, or is folded on-the-fly into required components
when considering CPS packages.
Note that this functionality is not exposed to the user at this time,
and is only used when resolving transitive dependencies for a CPS
package.
c3d279841b