Add a new step to accept recipient email for the recipient registration process

[yuetloo]

Problem:
If the environment variable, VUE_APP_GOOGLE_SPREADSHEET_ID, is defined, the optimistic recipient registration process will require the user to input an email address, and the email address is not recorded in the recipient registry contract.

This flow is broken with the introduction of the universal recipient registry which uses recipient metadata from an external source. Because the email is not available in the recipient metadata, a new page/step is needed in the recipient registration process to take the user email address when VUE_APP_GOOGLE_SPREADSHEET_ID is defined.

@auryn-macmillan , VUE_APP_GOOGLE_SPREADSHEET_ID, seems to be a new feature introduced post v0.6.0, please confirm if this feature should be retained.