Change authentication method with OAuth

[kenchan0130]

What I did

When using OAuth, I changed OAuth login specification like testlink users are linked by login column data instead of email column.

a12758f are main changes.

153baeb are format.

Motivation

Currently, when using OAuth, users are associated using the data in the email column of the users table.
This has several disadvantages.

1. End users can freely change their email address.
   • End users can impersonate another user at their will.
2. The email address has no unique guarantee.
   • User must be authenticated with a unique value.

[squash-labs]

Manage this branch in Squash

Test this branch here: https://kenchan0130fix-oauth-login-dhaci.squash.io

[kenchan0130]

@ maintainer
How is this going?

[fmancardi]

I need to understand if I want to add this to stable code or made it a configurable option

[kenchan0130]

I don't think it's appropriate to associate users in OAuth with values that the end user is free to change.

That's why I recommend introducing this as a stable code.

[fmancardi]

I understand but disagree with the idea of setting this as the standard way for oauth.
Surely a needed change is that email need to be populated and unique

[kenchan0130]

I agree with you. In that case, the email should be given a UNIQUE contract.

In addition, if you are using an external provider, it would be better if the email address is only available to the administrator role user to change each user's email address, for example.