API v2 GetPasswordResetEmail expects user to provide their ID

[kzalys]

Currently the GetPasswordResetEmail operation on API v2 expects the user to provide their ID in the request. If the user wants to reset their password, they probably cannot login and if they cannot login, they probably don't know their ID.

The operation should be updated to expect the user's email instead of their ID.

[kzalys]

The route definition for the GetPasswordEmail operation: https://github.com/unicsmcr/hs_auth/blob/master/routers/api/v2/router.go#L80
The implementation: https://github.com/unicsmcr/hs_auth/blob/master/routers/api/v2/users.go#L370

To resolve this issue we'd need to:

• Update the route for GetPasswordEmail to expect an email rather than a user id.
• Update the implementation for GetPasswordEmail. Note that the operation should still be usable with the me keyword (if the string me is provided instead of an email, the user should be derived from the auth token, example).
• Update GetPasswordEmail documentation and examples on the API reference: https://documenter.getpostman.com/view/2489646/T1DjjKP6?version=latest#c590f503-40a1-4fae-9c5c-6a85bcde48d4
• Update the unit tests for the GetPasswordEmail operation: https://github.com/unicsmcr/hs_auth/blob/master/routers/api/v2/users_test.go#L1153