Move the SamlIdGenerator

[phavekes]

This issue is imported from pivotal - Originaly created at Nov 25, 2019 by Michiel Kodde

In release 6.1 we moved the metadata generation features to the Symfony application. We did not move the 'SamlIdGenerator'. This generator is used to generate an unique id for SAML documents. (metadata, authnrequests and samlresponses).

Rule of thumb is to move any logic that is to be used in the SF application into the Symfony application (this can be a simple copy paste). But goal is to nog have a single depencency on library code in the new application.

What is to be done:

1. Move the Generator to the SF application
2. Make it into a service that is available in the DI container
3. Facilitate the new Generator, using the bridge feature back into the library
4. Et voila

Left-over from:
#168924689