New line shortcut should be option-return on Mac

[thomasst]

Current behavior:

When typing in single-line mode in Signal (v1.34.2) on macOS, Shift+Return inserts a new line and Option+Return sends the message. This is inconsistent with other macOS apps (e.g. Apple Messages) which use Option-Return to insert a new line.

Expected behavior:

• Option+Return should insert a new line
• Shift+Return should behave like Return and should send the message. (Alternatively, for compatibility, it could insert a new line).

[scottnonnenberg-signal]

Thanks @thomasst for letting us know that this has regressed: #4506 (comment)

[Mxchaeltrxn]

@scottnonnenberg-signal I'd be happy to do this one.

I'll see if I can get this working:

• Option+Return should insert a new line
• Shift+Return should behave like Return and should send the message.

I haven't contributed to Signal before so I might need some help if that's okay.

[kjs3]

@Mxchaeltrxn Did you ever attempt to make this change?