gh-96859: [argparse] Avoid copying lists on every append and extend action

[alexeypa]

Currently the append, append_const, and extend actions make a copy of the target list every time the action is called. It becomes rather slow with very long option lists.

Using the repro script from the issue description I could see the following results before and after this change.

Before:

➜  cpython git:(69a4063ca5) ✗ ./repro.py                                      
     256 iterations: 0:00:00.002216 s
     512 iterations: 0:00:00.003734 s
    1024 iterations: 0:00:00.009686 s
    2048 iterations: 0:00:00.018806 s
    4096 iterations: 0:00:00.048392 s
    8192 iterations: 0:00:00.130792 s
   16384 iterations: 0:00:00.399441 s
   32768 iterations: 0:00:01.341005 s
   65536 iterations: 0:00:05.148916 s
  131072 iterations: 0:00:20.325517 s

After:

➜  cpython git:(gh-96859_take2) ✗ ./repro.py                
     256 iterations: 0:00:00.001772 s
     512 iterations: 0:00:00.002994 s
    1024 iterations: 0:00:00.008132 s
    2048 iterations: 0:00:00.012443 s
    4096 iterations: 0:00:00.025432 s
    8192 iterations: 0:00:00.052343 s
   16384 iterations: 0:00:00.099193 s
   32768 iterations: 0:00:00.189960 s
   65536 iterations: 0:00:00.388533 s
  131072 iterations: 0:00:00.765152 s

• Issue: argparse.ArgumentParser is slow when parsing a very long option list #96859

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[alexeypa]

Nevemind, changing the signature of __call__ on 2cc48ba seems like a no go. It looks like the caller can pass a custom action class to action, so this will break existing clients. Let me see if there is a better way to do this.