* Update alpine version to 3.13 

alpine 3.12 has a CVE https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-28928 which got fixed in recent version

* address review comments

* Use comma separated value for multiple claims

* Fix lint error

* Fix more tests

* Fix one more test

* Always flatten the headers

* Ensure we test the real multi-groups

* Only update map when necessary

* Update CHANGELOG

* Move to the right location of change log

* Fix blank line

* Add sensible logging flag to default setup for logger

* Use logger instead of fmt for info logging with sensible data

* Remove sensible logging flag

* Update CHANGELOG.md

Co-authored-by: Joel Speed <Joel.speed@hotmail.co.uk>

Add docs and generated reference for Alpha configuration

Track the ReverseProxy config setting in the request Scope

Additionally, convert a lot of helper methods to be private

Reorganized the structure of the Request Utils due to their widespread use
resulting in circular imports issues (mostly because of middleware & logger).

This allows for proper handling of reverse proxy based headers throughout
the lifecycle of a request.

Add Security Policy

Adapt isAjax to support mimetype lists

Fixes #988

Add NickMeves to MAINTAINERS

* properly handle splitted cookies with names ending with _

* test update

* provide cookieName into joinCookies instead of processing the suffix

* changelog update

* test update

Refactor Keycloak Provider Methods

Group/Role Access Restriction support in `/oauth2/auth` endpoint 

OIDC Provider Refactor