Add ability to Filter results from NLP extractors

[zeusorionIBM]

Description:
An extractor sometimes produces unwanted results even though the pattern is a match. These unwanted results can often be recognized by other text near the match in the document. To further restrict matches, give the user the ability to create a filter. More information can be found here.

Tasks:
The filter node and panel are already part of the Elyra NLP Canvas. We need to:

• validate that all required input from the user is entered and correct
• transform user's input into payload that SystemT can then translate and run as AQL.

[JesusGuerrero]

Additional Filters:

Range: Add Equals, StartsWith, EndsWith, OccursBefore, OccursAfter
Length: Add ShorterThan, LongerThan, Equals, (with 1 input concept/attribute & input for integer & toggle between characters/tokens)
Text: All of them (1 input for custom regular expression, & 2 hash maps for case sensitivity)