Feat: handle ephemeral handler

[Stef-Rousset]

🎩 Description

This PR handles the ephemeral sms vote in the handler which is plugged on the ephemeral verification of decidim.

Testing

1. Go to /system and ensure that the ephemeral authorization is checked for the organization
2. As an admin, go to the configure page of a budget with several projects and where the vote is allowed > manage permissions > check the ephemeral authorization on the vote
3. As a non logged in user, go to that budget and click on vote.
4. Enter your phone country and phone number (screenshot one) and submit
5. Go to the logs on your terminal and search for "Example SMS gateway service, verification code is: ", and then enter the code in the form (screenshot two)
6. Vote for one project, and then click on "Back to budgets" and then to the Close X to end the ephemeral session (screenshot Three).
7. Repeat the steps 3 to 5 with the same phone country and phone number, and see that the project you voted before is still added to the budget, then finish your vote.
8. Repeat the steps 3 to 5 with the same phone country and phone number, and see that you are on the page with finished vote for that budget.

📌 Related Issues

• Related to https://github.com/orgs/OpenSourcePolitics/projects/26/views/1?pane=issue&itemId=136621724&issue=OpenSourcePolitics%7Cintern-tasks%7C204

Tasks

• Add specs
• In case of new dependencies or version bump, update related documentation

📷 Screenshots

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