Add option to modify the number of cores

[AfzalivE]

As discussed in #126, the emulator being set up by avdmanager in the new command-line tools only uses 1 core, which affects the stability of the emulator negatively sometimes.

In our experience, 2 cores seem to be pretty solid with no (or almost no) System UI ANR dialogs being shown on boot.

Appending a new line with a duplicate hw.cpu.ncore overrides other lines defining the same property before it.

Please let me know if you'd like me to add this option in workflow.yml file as well so that the tests include this option as well. Wasn't sure about updating that.

[ychescale9]

Thanks!

Please let me know if you'd like me to add this option in workflow.yml file as well so that the tests include this option as well. Wasn't sure about updating that.

Yes let's do this.

I'm also keen to add a default value (2) for core so we don't need to ask users to opt in to see if this improves stability (unless they pin the action to a specific version). What do you think?

[AfzalivE]

I'm also keen to add a default value (2) for core so we don't need to ask users to opt in to see if this improves stability (unless they pin the action to a specific version). What do you think?

I think this would be good and doesn't severely impact Gradle compilation while the emulator is running, in my experience. Updated.

[ychescale9]

Thanks! I’ll try to do a release this weekend.