Merge topic 'cleanup-target-types'

ef796cc743 cmGeneratorTarget: Skip computing link implementation for custom targets
45158b2afe cmGeneratorTarget: Simplify logic in ComputeLinkInterfaceLibraries
d6b1f5704e cmGeneratorTarget: Add missing nullptr checks
7695b67500 cmComputeTargetDepends: Add missing nullptr check
95b5df8646 cmGeneratorTarget: Skip computing languages for custom targets
2f0790df50 Factor out generator checks for filtering on non-compiling targets
422d9a0ab2 Factor out generator checks for filtering out interface libraries
bce82df0aa cmGeneratorTarget: Remove unnecessary target type check in dependency tracing
...

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Kyle Edwards <kyle.edwards@kitware.com>
Merge-request: !5038