[Public-form] - Allow usage of private form without plugin invitation installed

[Public-form] - Allow usage of private form without plugin invitation installed

In the context of an SP (Service Provider), the IDP (Identity Provider) authenticate the user but the SP requires local registration of such users in order to manage required applications access.

The SP therefore issue a "private-form" allowing headers sent by the IDP to fill-in presented fields of the form. Private-form, as of today, requires invitations plugin and is mandate to verify tokens.

For the SP, a token is now required and an "invitation" is not mandatory. Rending the plugin invitations obsolete but the private-form unsuable due to lack of tokens.

The MR should resolve this problems by adding a "backend configuration" boolean field, allowing the usage of private-form without the plugins invitation installed.