Fix ContentView view

[shweta83]

There were few minor fixes needed for new contentview view and entities.

• Contentview Views:

1. version_dropdown = Dropdown(
   locator='.//div[@data-ouia-component-id="cv-version-header-actions-dropdown"]'
   )
   locator was mentioned twice in views which could be confusing.
2. Fixed lce_selector locator.

• Contentview Entities:

1. Renamed version_name variable to version to maintain consistency in the module.
2. def promote does not handle errors in case incorrect lce or invalid promote happens, added a check for handing and reading the error message.
3. There is no lce variable in views so updated it to lce_selector.
4. Updated class PromoteContentViewVersion in views

[vijaysawant]

trigger: test-robottelo
pytest: tests/foreman/ui/test_contentview.py -k 'test_positive_end_to_end'

[sambible]

ACK, thanks for cleaning up some of the cruft in here.

[shweta83]

The test failing due at content-view-repositories-table which is unrelated to the change.

[vijaysawant]

Changes looks good to me, please run PRT for test from robottelo PR 17530
Ack, (Wait for PRT to pass)

[LadislavVasina1]

Airgun addition looks good, let's wait for the PRT

[chris1984]

Approved per PRT being green