Valid generated Jenkinsfiles checks moved into generate_command_pipeline
Valid generated Jenkinsfiles checks moved into generate_command_pipeline

Also, added unique name check for parallel_branch names too, to avoid:
```
org.jenkinsci.plugins.workflow.cps.CpsCompilationErrorsException: startup failed:
Script1.groovy: 150: Duplicate named parameter 'run @ dmake-test/test-external-dependency-nginx' found. at line: 150 column: 9. File: Script1.groovy @ line 150, column 9.
           'test @ dmake-tutorial/worker': {
           ^

1 error
```

Deepomatic/dmake,Deepomatic/dmake,Deepomatic/dmake,Deepomatic/dmake