Add optional PKCE flow to OIDC strategy (#308)
* Initial attempt at PKCE for SSO
* pKCE changeds wip
* PKCE working
* uncommit enabled auth
* fix unit test
* add query param signature
* generate new files
* prettify
* dont commit config
* revert makefile
* test
* Revert
* cookie import
* generate properly
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Co-authored-by: Alex W <alex@blinkenlights.ca>
