OIDC: Log in (#3554)

* use oidc-client-ts during oidc discovery

* export new type for auth config

* deprecate generateAuthorizationUrl in favour of generateOidcAuthorizationUrl

* testing util for oidc configurations

* test generateOidcAuthorizationUrl

* lint

* test discovery

* dont pass whole client wellknown to oidc validation funcs

* add nonce

* use oidc-client-ts for oidc response

* validate user state and update tests

* use oidc-client-ts for code exchange

* use oidc-client-ts in completing auth grant

* use client userState for homeserver

* more comments

src/oidc/error.ts

@@ -25,4 +25,5 @@ export enum OidcError {
     CodeExchangeFailed = "Failed to exchange code for token",
     InvalidBearerTokenResponse = "Invalid bearer token response",
     InvalidIdToken = "Invalid ID token",
+    MissingOrInvalidStoredState = "State required to finish logging in is not found in storage.",
 }