Improve OVAL test info

[Honny1]

This PR adds:

• OVAL state to OVAL test info
• check and check_existence attributes to OVAL test info

[evgenyz]

There is a conflict. Can you please rebase the PR?

[jan-cerny]

@Honny1 If you do some changes you need to summarize them in a comment in the PR so that the visitors know what changed.

[Honny1]

@jan-cerny Okay.

Changes:

• Removed shared static method for transition list of tuples to dictionary and create a dictionary in the first place,
• Created unit tests for shared methods,
• Reversed if condition in method _get_ref_var,
• Added tooltip info to check, check_existence and to id of objects and state. See the image below.

[Honny1]

Changes:

• Simplified get_test_info method,
• Improved tooltip text for check and check_existence attributes.

[Honny1]

Changes:

• Improved tooltip text for check and check_existence attributes,
• renamed out variables,
• removed wrapping array in return,
• Used a more pythonic way to contact strings.