debugger: wait for initial break render during startup

[inoway46]

node inspect <script> startup could display the debug> prompt before the initial break output had been rendered.
ex. https://github.com/nodejs/node/actions/runs/28076627608

This updates initial local script startup to wait for the first Debugger.paused render before creating the REPL prompt, preserving the expected startup output order:

Debugger attached.
 ok
Break on start in ...
debug>

This wait only applies to initial local script startup and is released on startup exceptions, client close, or child exit. Other debugger flows are unchanged.

Testing

ninja -C out/Release node
./tools/test.py -p actions parallel/test-debugger-run-restart-init
./tools/test.py -p actions parallel/test-debugger-help
./tools/test.py -p actions sequential/test-debug-prompt
./tools/test.py -p actions parallel/test-debugger-restart-message
./tools/test.py -p actions parallel/test-debugger-exceptions parallel/test-debugger-run-after-quit-restart
VERBOSE=1 out/Release/node test/parallel/test-debugger-auto-resume.mjs

[inoway46]

This keeps sequential/test-debug-prompt from hanging when node inspect foo fails before the initial Debugger.paused render and the REPL would otherwise never reach debug>.

failed log: https://github.com/nodejs/node/actions/runs/28320440600/job/83901478505?pr=64189#step:8:6114

[inoway46]

The original flake that motivated this PR now appears to be addressed by #65194
This PR still addresses a separate initial-break render ordering gap, but given its limited impact and the additional startup synchronization complexity, I don't think it's worth pursuing at this point.
Closing for now; we can revisit if the ordering issue becomes observable in practice.