gh-107932: Fix dis module for bytecode that does not have an associated source line

[CorvinM]

Fix dis module for bytecode that does not have an associated source line.
fixes#107932

This does change behavior of many of the dis.py public functions to display lines with no source line mapping as such.
At the very least it changes:
findlinestarts - now returns starts of bytecode blocks that dont have a source line with lineno=None
dis/disassemble/distb/disco - now separates and labels lineno=None bytecode blocks, previously it lumped them into the previous block (see #107932)
get_instructions & Instruction - Instruction objects now have starts_line=False to indicate that the instruction does not start a line.

• Issue: dis.dis() reports line numbers where there are none. #107932

[ghost]

All commit authors signed the Contributor License Agreement.

[bedevere-bot]

Most changes to Python require a NEWS entry.

Please add it using the blurb_it web app or the blurb command-line tool.

[markshannon]

Thanks for working on this.
The changes look correct, but the use of False as a special value for starts_line is a bit hard to follow.

Lib/test/test_dis.py is an endless source of merge conflicts, so I'll try merge ASAP after you've made the changes.

[bedevere-bot]

A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

[CorvinM]

@markshannon Thanks for the quick review! I have made the requested changes; please review again. I have also updated the docs to reflect the changes and resolved the merge conflict (for now). I've listed the changes in the docs as happening in 3.13 (is this the correct procedure for the project?)

[bedevere-bot]

Thanks for making the requested changes!

@markshannon: please review the changes made to this pull request.

[markshannon]

Thanks, looks good.

[erlend-aasland]

main has been broken since this was merged.

[markshannon]

#108478