Clean-up old settings and code

[esune]

Over time, VC-AuthN has evolved significantly and in order to retain backwards-compatibility several settings to control how the code were introduced. With the deprecation of AIP 1.0, many of these settings are now obsolete and it would be beneficial to remove them, as well as the branches of code that were executed based on those configurations.

A couple of the items to look at are:

• USE_OOB_PRESENT_PROOF: while using a service decorator is still possible, we may want to simplify by removing the option and defaulting to out-of-band, that seems to be more broadly accepted/adopted.
• USE_URL_DEEP_LINK: this should be the default (and likely only) behaviour supported.

[loneil]

#752 merged in

Tracked removal stuff for bcgov deployments that can be done eventually on release here bcgov/trust-over-ip-configurations#305