Fix "Protected Terms" formatting

[koppor]

Test bib:

@Article{demo,
  title  = {BPMN4TOSCA rocks in BPMN and TOSCA},
}

1. Enable custom list "custom" in the preferences. Result:
   
2. Open the entry editor of demo entry. Navigate to the title field.
3. Place the cursor to the beginning of BPMN4TOSCA.
4. Right click - go to Protected terms - Add selected text to list. (nothing can be selected)
   
5. Double click on BPMN4TOSCA
6. Add to list
   
7. List has space at the end
   
8. Add BPMN (using a double click)
9. Add TOSCA (using a double click)
10. Execute "Protect terms"
    
11. Result: {}{BPMN}{}4TOSCA rocks in {}{BPMN}{} and {}{TOSCA}{}
12. Modify demo.terms manually: Remove spaces at the end.
    
13. Execute "Protect Terms"
14. Result: {}{BPMN}{}4TOSCA rocks in {}{BPMN}{} and {}{TOSCA}{}

These points have to be fixed:

• Step 4: It should be possible to add the term to current word to the list - even if nothing is selected. A right click and then "Add text to selected list" should simply add the current word to the list
• Step 6: The selected text should be trimmed
• Step 14: There should be no {} contained. --> {BPMN4TOSCA} rocks in {BPMN} and {TOSCA}
• In general, longer terms should be treated first (to avoid substring issues)
• Reiterating on "Format field" should not lead to multiple {}: {}{}{}{}{}{}{}{BPMN}{}{}{}{}{}{}{}4TOSCA rocks in {}{}{}{}{}{}{}{BPMN}{}{}{}{}{}{}{} and {}{}{}{}{}{}{}{TOSCA}{}{}{}{}{}{}{}

Also add test cases.

[yuyan-z]

Hi, is anyone currently working on this issue? If not, we would like to have it as our course project.
We are 7 students from IMT Atlantique and we are expected to finish a contribution on the 19 December.
Best regards.

[github-actions]

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[Siedlerchr]

@yuyan-z Thanks for your interest, you are welcome! the issue is free to take. I will put it now on reserved and assign you

[yuyan-z]

Thank you so much! We will start working on it and create a draft pull request as soon as possible