Add LABEL and LABEL_NAME to the ct_add_dir() function to specify CTes…

[Risto97]

…t label for the tests

Is this pull request associated with an issue(s)? Please list issues associated with this pull request, including closing words as appropriate. Resolves #112

Description Describe what this pull request will accomplish. It will allow for tests added with ct_add_dir to be labeled using LABEL and LABEL_NAME arguments.

• LABEL will use label of the tests as relative directory path used with ct_add_dir call.
• LABEL_NAME has higher priority and allows to label the tests in the directory to any name.

TODOs For draft pull requests please include a list of what needs to be done and check off items as you complete them.

[CLAassistant]

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