(GLUE-1812) Operations for extractors and variants

There are additional operations available for Glue Extractors in Extractor Workbench:

• Manage - display main information about extractor in Extractor Definition and show Extractor Request Browser
• Display – shows extractor/variant settings in read-only mode
• Edit – opens extractor/variant in edit mode, if the extractor/variant is not active. If active then the extractor/variant is open only in Display (read-only) mode
• Delete – deletes the selected extractor/variant

• Create Variant - one of the possibilities how to create Variant
• Activate all variants - activation of all variants for the selected extractor
• Deactivate all variants - deactivation of all variants for the selected extractor
  
  

_{Operations for Extractor/Variant}