Add form type for reset password request

[jordisala1991]

Subject

I am targeting this branch, because this breaks BC.

Closes #784
Part of #1465

Changelog

### Added
- Added `ResetPasswordRequestFormType` form type.

[jordisala1991]

I have unified both the request of the password reset and the POST route. This way we can take advantage of the Symfony form validations and show errors to the user if he submits invalid data (no data in this case is the only considered invalid).

I have also added more functional tests to ensure when we submit invalid data on both forms we get proper response.

I don't like a lot having 10 dependencies for one controller but refactoring that requires more classes, so the idea is that we choose between:

1. Not using Symfony forms in the reset password request and have separate controllers (no validation, but whatever)
2. Use Symfony forms in the reset password request and have one controller (it can be refactored later, but not sure if I will invest more time to it)

wdyt @VincentLanglet , is it worth?

[VincentLanglet]

Use Symfony forms in the reset password request and have one controller (it can be refactored later, but not sure if I will invest more time to it)

I'm ok with this so far