Revert "cmGeneratorTarget: Compute target objects in LookupObjectLibraries."

This reverts commit 46019f89e555341c2b42d824e947c8a9e1d32751.
Revert "cmGeneratorTarget: Remove GetObjectName method."

This reverts commit 32a6fdb59e1beb36c567a7fcfa83c7eebdef03e7.
Revert "cmLocalGenerator: Add ComputeObjectFilename method."

This reverts commit f94cf6285b2317441753c8e425b465d86c8987e6.
Merge topic 'target-objects-refactor' into next

34e88e8c Revert "cmLocalGenerator: Add ComputeObjectFilename method."
06232ea5 Revert "cmGeneratorTarget: Remove GetObjectName method."
50845598 Revert "cmGeneratorTarget: Compute target objects in LookupObjectLibraries."