Use default max_lines when calling up & down

[HeyNonster]

Description

Both up and down only show 1 source line when called, I think it would be more useful if they provided more context. This removes the max_lines: 1 kwarg when they call show_src. max_lines in show_src will default to CONFIG[:show_src_lines]¹.

Big thanks to @st0012 for showing me and @bquorning where this behavior is defined.

Footnotes

1. (https://github.com/ruby/debug/blob/0b77e8294b5b220b3b2a089bf09f94808654899a/lib/debug/thread_client.rb#L510) ↩

[st0012]

I want to second this proposal as I also often need to chain whereami after moving to a different frame, which IMO is not the best user experience in most cases.

[HeyNonster]

Also probably useful to note that byebug displays more lines by default making it quite a difference switching from byebug to debug:

byebug-vs-debug.mov

[launchable-app]

Launchable Report

❌ Test session #2907805 failed   details on CI
_{🔔 no issues ✖️1 test failed ✔️63 tests passed}

❌ Test session #2907807 failed   details on CI
_{🔔 no issues ✖️1 test failed ✔️63 tests passed}

Passed test sessions

✅ Test session #2907791 passed   details on CI
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✅ Test session #2907857 passed   details on CI

Build: refs_pull_1094_merge_b1963e7b72554c9672900ba046c3088598955488

[HeyNonster]

Seems the protocol tests are flaky: #1060