Merge topic 'cmake-ninja-workdir'

2725ecff38 Ninja: Handle depfiles with absolute paths to generated files
bc40cd7a4e Tests: Add case covering a unity build with a generated source
ae927f936d cmGlobalNinjaGenerator: Improve allocation pattern in WriteBuild
68e5f92cad cmGlobalNinjaGenerator: Factor out custom command output collection
c5195193d3 cmGlobalNinjaGenerator: Reduce string copies in WriteCustomCommandBuild
8bac527b0c cmGlobalNinjaGenerator: Re-order logic in WriteCustomCommandBuild
ddc030f5ca cmGlobalNinjaGenerator: Record implicit outputs as known too
ceb82752ef cmLocalNinjaGenerator: Use variable for main custom command output path

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !6143