Fix reverse debugging commands

[loganwendholt]

• I have added an entry to docs/changelog.md

Summary of changes

Fixed reverse debugging commands that were broken when --gdb flag was removed.

Before this fix, replaying an rr recording would force all debugging commands to be run in reverse mode, with no checkbox available to override the setting.

Also pinned mypy to its previous version, since the latest update broke linting and caused all CI to fail.

Test plan

Tested by building the executable with nox --sessions build_executable_linux, then ran gdbgui on a previously recorded rr session with

./gdbgui_0.14.0.2 --gdb-cmd "rr replay --"

and confirmed reverse debugging commands (and the UI itself -- tooltips, etc.) were behaving as expected.

Also ran normally with

./gdbgui_0.14.0.2

[cs01]

Thanks for this! Looks like I broke it during that update, my bad. LGTM but the lint job is failing.

[loganwendholt]

Linter issue should be fixed, but I did just spot one last-minute typo -- will push again in just a sec.

[loganwendholt]

Should be good to go!

[cs01]

Thanks again 😃