gh-142250: Add hasjforward and hasjback collections to opcode.py and document in dis.rst

[khanak0509]

Add new opcode collections hasjforward and hasjback to distinguish between forward and backward jump instructions, addressing the needs of third-party bytecode libraries.

Change :

(1) Lib/opcode.py

• Added hasjforward and hasjback to __all__ exports
• Implemented _is_backward_jump_op() helper function
• Created hasjforward collection (12 forward jump opcodes)
• Created hasjback collection (4 backward jump opcodes: JUMP_BACKWARD, JUMP_BACKWARD_NO_INTERRUPT, FOR_ITER, END_ASYNC_FOR)

(2) Doc/library/dis.rst

• Documented hasjforward collection with .. versionadded:: 3.14
• Documented hasjback collection with examples including END_ASYNC_FOR

for testing :
./python.exe -c "from opcode import hasjforward, hasjback; print('hasjforward:', len(hasjforward)); print('hasjback:', len(hasjback))"

Output: hasjforward: 12, hasjback: 4

./python.exe -c "from opcode import hasjback, opmap, opname; print([opname[op] for op in hasjback])"

Output: ['END_ASYNC_FOR', 'FOR_ITER', 'JUMP_BACKWARD', 'JUMP_BACKWARD_NO_INTERRUPT']

./python.exe -m test test_dis

Result: PASSED

issue #142250

• Issue: END_ASYNC_FOR expects an undocumented argument in 3.14 #142250

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📚 Documentation preview 📚: https://cpython-previews--142281.org.readthedocs.build/

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[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.

[MatthieuDartiailh]

The News fragment should mention the fix to the END_ASYNC_FOR documentation.
Also while the fix should be backported to 3.14, the addition of the hasjforward is unlikely to be so it may be better to split the work in two.

[khanak0509]

I have added News fragment to the END_ASYNC_FOR documentation in latest commit but what do you mean by "Also while the fix should be backported to 3.14, the addition of the hasjforward is unlikely to be so it may be better to split the work in two."
could you please elaborate . do I have to create two PR for each change one for dis.rst and second for opcode.py ?