Remove redundant cmake::GetIsPropertyDefined method

We already have cmake::IsPropertyDefined for the same reason.
Cleanup some variable documentation names

Remove trailing whitespace after property names.
Remove duplicate CMAKE_<LANG>_LINK_EXECUTABLE definition.
Rename "[Project name]" placeholder to "<PROJECT-NAME>".
Merge topic 'cleanup-properties' into next

b78bc33 Cleanup some variable documentation names
bbfff52 Remove redundant cmake::GetIsPropertyDefined method