[dmt] oss.yaml should be present only for those modules that have the images folder

[RottenRat]

No images -> nothing to license -> oss.yaml is not needed
Tests:
Before:
Case: No images dir

🐒 [oss (#module)]
     Message:      Module should have oss.yaml
     Module:       test
     FilePath:     /test/test/oss.yaml

After:
All OK

Case: has images dir
Before:

🐒 [oss (#module)]
     Message:      Module should have oss.yaml
     Module:       test
     FilePath:     /test/test/oss.yaml

After:

(WARN)
🐒 [oss (#module)]
     Message:      module has images folder, so it likely should have oss.yaml
     Module:       test
     FilePath:     /test/test/oss.yaml

Case: has oss.yaml (empty) but have no images dir
Before:

🐒 [oss (#module)]
     Message:     no projects described
     Module:      test
     FilePath:     /test/test/oss.yaml

After
All OK

Else errors work same