Meta: list of bugs in`cwltool --pack`

Open `--pack` related issues to confirm that `cwlpack` fixes:
- [ ] Inconsistent behaviour in packing #1470
- [ ] cwltool --pack generates IDs for enum symbols #1513
- [ ] Behavior of cwltool --pack is inconsistent when tool has an ID #1512
- [ ] 'main/' added when 'id' not present in workflow outputs #1436
- [ ] Not possible to pack workflow A with reference to packed workflow B #1323
- [ ] cwltool pack creates invalid json when sub-attributes are named the same #1277
- [ ] Workflow fails validation after packing #1241
- [ ] Packing Error: relative path to tools are falsely handled as absolute #1240
- [ ] unpack a workflow #1211
- [ ] '--pack' option fails when '--validate' works fine #1103
- [ ] regression: --pack, relative run references when loading from a URL #1077
- [x] cwltool --pack : field $schemas get lost #897
- [ ] Enhance --pack to replace default Files with File literals? #531