As a developer, I would like default test accounts to be auto-generated by Firebase emulator.

[emaela]

Have yarn emulate include automatically adding default emulator accounts for:

• Selecting 2
• Selecting 4
• Selecting 8
• Pairing 2
• Pairing 4
• Pairing 8
• Admin account

This can be done by creating default accounts and then using yarn export to save them.