Feature/custom OIDC scope

[gpongelli]

Description

This PR add the sdk side to manage OIDC custom scopes, as it can be already done with WEB_OIDC_SCOPE .

Related Issue

opencloud-eu/ios#27

Motivation and Context

When managing custom roles through LLDAP and Authelia, OpenCloud does not work correctly due to fixed OIDC scopes, see discussion linked in related issue opencloud-eu/ios#27 .
A solution could be to add a custom scopes field into iOS app, and accept it server-side as same as it was done for WEB_OIDC_SCOPE.

How Has This Been Tested?

Manually

Screenshots (if appropriate):

no screenshot

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.
• All new and existing tests passed.