firebaseAdminInitConfig is missing the storageBucket field

[se210]

Is your feature request related to a problem? Please describe.
When using the Firebase Admin SDK, the storage bucket is not properly initialized because firebaseAdminInitConfig is missing the storageBucket field.

Describe the solution you'd like and how you'd implement it
Add storageBucket?: string to firebaseAdminInitConfig

Is this a breaking change?
No

Describe alternatives you've considered
I am currently working around the Typescript error by doing:

firebaseAdminInitConfig: {
  ...
  storageBucket: "my-config"
} as unknown as any