[PR] Add Automata.makeCharSet(int[]) to optimize caseless matching. [lucene]

[via GitHub]

rmuir opened a new pull request, #14193:
URL: https://github.com/apache/lucene/pull/14193

   Previously caseless matching was implemented via code such as this:
   
   ```java
     Operations.union(Automata.makeChar('x'), Automata.makeChar('X'))
   ```
   
   Proposed unicode caseless matching (#14192) implements it with repeated 
unions:
   
   ```java
     a1 = Operations.union(Automata.makeChar('x'), Automata.makeChar('X'))
     a2 = Operations.union(a1, Automata.makeChar('y'))
     a3 = Operations.union(a2, Automata.makeChar('Y'))
   ```
   The union operation doesn't return a minimal automaton: improving union 
would always be nice, but this change offers a simple api for the task that 
returns half the number of states.
   
   Before: caseless match of "a":
   
![a_before](https://github.com/user-attachments/assets/5f1f7cc2-a792-434f-98ec-a5e629678f16)
   
   After:
   
![a_after](https://github.com/user-attachments/assets/aa60f883-cfd4-4291-9fb7-1bbecf0825ea)
   
   Before: caseless match of "lucene":
   
![lucene_before](https://github.com/user-attachments/assets/76e38dc6-5cb4-4b77-923a-22dbab345241)
   
   After:
   
![lucene_after](https://github.com/user-attachments/assets/3ca7755e-826d-4f79-b22e-8a514497d69e)
   
   Just like the `union`, the `concatenate` adds some useless states, but they 
are less of a problem than the ones from before.
   
   I didn't try anything more such as repeated union or kleene star, to see if 
I could make a really bad case, I felt like this was good enough, to get it to 
a better place. We can look at optimizing union/concatenate separately still, 
but that's always more dangerous and tricky.
   


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