Enhancements for `--terms` flag

[ShweataNHegde]

Is your feature request related to a problem? Please describe. The feature request isn't necessarily related to a problem. With the --terms flag, it would be useful to have functionalities such as:

• Ignore the comma at the end of the text file because spurious commas will create an incorrect query
• supporting multiple files with a custom boolean operator between them.

 --term file1.txt file2.txt 

• including AND and NOT logic (between the terms in the text file and between files) - this can get complicated very quickly!
• NOT logic would be valuable if we want to define a custom stopword list while querying.

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