Github and Google Mail censuses types

[jpaulet]

Integrate into the vocdoni.app the new Github & Gmail census to be able to vote trough the those social networks.

Reference: https://github.com/vocdoni/ui-scaffold/pull/526

Pending Tasks:

• [x] Create the OAuth service
• [x] Integrate the new census into the UI (like wallet addresses, but with emails)
• [x] Be able to add a new metadata to the election, to specify the census type (Github/Gmail)
• [ ] Deploy csp census for stage and lts: https://github.com/vocdoni/ui-scaffold/issues/496
• [ ] Add the Github improvements: https://github.com/vocdoni/ui-scaffold/issues/620
• [ ] Include the two new census in the .env file on Vocdoni.app.
• [ ] Tests

Extra:

• [ ] [Github] https://github.com/vocdoni/ui-scaffold/issues/497
• [ ] https://github.com/vocdoni/ui-components/issues/134
• [ ] In the voting page, when login, only show the oAuth login type specified