Unify frame and locals collection implementation between ThreadClient and servers

[st0012]

1. Use get_frame to retrieve frames with the given frame index.
2. Use collect_locals to retrieve the locals from the given frame.
   • This also fixes an issue that %self isn't displayed in DAP when stepping backward.

Thanks to the DAP tests written by @ono-max, I feel a lot comfortable doing such refactoring now 👍

[ono-max]

Could you wait for refactoring CDP part until I'm done creating the test framework for CDP?
Thanks.

[st0012]

@ono-max I can drop the changes for CDP server if you concern about the test coverage.

[ono-max]

That sounds good. Could you drop it? Thank you.

[st0012]

@ono-max done 👍

[ko1]

why dap tests are changed?

[ono-max]

Could you rebase this PR so that we can confirm if your changes work in CI?

[st0012]

@ono-max rebased and it passed 👍

[ono-max]

Sorry, if you're ok, could you use the test generator instead of modifying tests directly to rewrite tests?

[st0012]

@ko1 I hope this can also be merged first if possible. I'll add more variables tests with #559

[ono-max]

Did you fix tests with the test generator?

[st0012]

No. I plan to use the new assert_locals_result (or whatever you plan to call it) to test it.
The whole idea of adding unit-tests is that I don't need to rerun integration tests for changes like this.

[ko1]

Sorry for absent. I'll merge it and I revisit to consider about the name get_frame

[st0012]

@ko1 thank you 🙏