fix(cli): Specify keystore alias and alias password build options for apksigner

[bentleyo]

There are two issues with how apksigner is called that have been identified in #7054.

• If the keystore contains multiple keys the alias needs to be specified otherwise an error is thrown
• If the key has a password the cli will hang as apksigner prompts input for the key password

We can get around this by specifying the required parameters for apksigner.

[theproducer]

Since --ks-key-alias and --key-pass are optional, i'd rather signingArgs be built in a way to exclude those flags if they are not set.

[bentleyo]

@theproducer I have updated the PR mate, are you happy with this approach?