fix: set default menu in will-finish-launching event

[zcbenz]

Description of Change

Close #23026, which was regressed due to setDefaultApplicationMenu being changed to use whenReady. When user uses ready event directly, their callback would be called before setDefaultApplicationMenu() and the default menu would override their menu settings.

It is hard to ensure the setDefaultApplicationMenu is called before user's ready callbacks, especially when promises are involved. However we can use the will-finish-launching event which is guaranteed to be called before the ready event, and we have explicitly documented that users should only create window after the ready event.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• tests are changed or added
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fix win.setMenuBarVisibility(false) not hiding menu bar.

[release-clerk]

Release Notes Persisted

Fix win.setMenuBarVisibility(false) not hiding menu bar.

[trop]

I have automatically backported this PR to "9-x-y", please check out #23263