feat: Token Revocation, Request Object and OP Certification (#130)

FEATURES (and FIXES):
- support OAuth 2.0 Token Revocation [RFC 7009](https://datatracker.ietf.org/doc/html/rfc7009)
- handle request object using `request` parameter [OIDC Core 1.0 Request Object](https://openid.net/specs/openid-connect-core-1_0.html#RequestObject)
- handle response mode
- added some information to the discovery endpoint:
  - revocation_endpoint (added with token revocation) 
  - revocation_endpoint_auth_methods_supported (added with token revocation)
  - revocation_endpoint_auth_signing_alg_values_supported (added with token revocation)
  - token_endpoint_auth_signing_alg_values_supported (was missing)
  - introspection_endpoint_auth_signing_alg_values_supported (was missing)
  - request_object_signing_alg_values_supported (added with request object)
  - request_parameter_supported (added with request object)
 - fixed `removeUserinfoScopes ` now returns the scopes without "userinfo" scopes (profile, email, phone, addedd) [source diff](https://github.com/caos/oidc/pull/130/files#diff-fad50c8c0f065d4dbc49d6c6a38f09c992c8f5d651a479ba00e31b500543559eL170-R171)
- improved error handling (pkg/oidc/error.go) and fixed some wrong OAuth errors (e.g. `invalid_grant` instead of `invalid_request`)
- improved MarshalJSON and added MarshalJSONWithStatus
- removed deprecated PEM decryption from `BytesToPrivateKey`  [source diff](https://github.com/caos/oidc/pull/130/files#diff-fe246e428e399ccff599627c71764de51387b60b4df84c67de3febd0954e859bL11-L19)
- NewAccessTokenVerifier now uses correct (internal) `accessTokenVerifier` [source diff](https://github.com/caos/oidc/pull/130/files#diff-3a01c7500ead8f35448456ef231c7c22f8d291710936cac91de5edeef52ffc72L52-R52)

BREAKING CHANGE:
- move functions from `utils` package into separate packages
- added various methods to the (OP) `Configuration` interface [source diff](https://github.com/caos/oidc/pull/130/files#diff-2538e0dfc772fdc37f057aecd6fcc2943f516c24e8be794cce0e368a26d20a82R19-R32)
- added revocationEndpoint to `WithCustomEndpoints ` [source diff](https://github.com/caos/oidc/pull/130/files#diff-19ae13a743eb7cebbb96492798b1bec556673eb6236b1387e38d722900bae1c3L355-R391)
- remove unnecessary context parameter from JWTProfileExchange [source diff](https://github.com/caos/oidc/pull/130/files#diff-4ed8f6affa4a9631fa8a034b3d5752fbb6a819107141aae00029014e950f7b4cL14)

pkg/oidc/authorization.go

@@ -42,6 +42,9 @@ const (
 	DisplayTouch Display = "touch"
 	DisplayWAP   Display = "wap"
 
+	ResponseModeQuery    ResponseMode = "query"
+	ResponseModeFragment ResponseMode = "fragment"
+
 	//PromptNone (`none`) disallows the Authorization Server to display any authentication or consent user interface pages.
 	//An error (login_required, interaction_required, ...) will be returned if the user is not already authenticated or consent is needed
 	PromptNone = "none"
@@ -59,27 +62,28 @@ const (
 //AuthRequest according to:
 //https://openid.net/specs/openid-connect-core-1_0.html#AuthRequest
 type AuthRequest struct {
-	ID           string
-	Scopes       SpaceDelimitedArray `schema:"scope"`
-	ResponseType ResponseType        `schema:"response_type"`
-	ClientID     string              `schema:"client_id"`
-	RedirectURI  string              `schema:"redirect_uri"` //TODO: type
+	Scopes       SpaceDelimitedArray `json:"scope" schema:"scope"`
+	ResponseType ResponseType        `json:"response_type" schema:"response_type"`
+	ClientID     string              `json:"client_id" schema:"client_id"`
+	RedirectURI  string              `json:"redirect_uri" schema:"redirect_uri"`
 
-	State string `schema:"state"`
+	State string `json:"state" schema:"state"`
+	Nonce string `json:"nonce" schema:"nonce"`
 
-	// ResponseMode TODO: ?
+	ResponseMode ResponseMode        `json:"response_mode" schema:"response_mode"`
+	Display      Display             `json:"display" schema:"display"`
+	Prompt       SpaceDelimitedArray `json:"prompt" schema:"prompt"`
+	MaxAge       *uint               `json:"max_age" schema:"max_age"`
+	UILocales    Locales             `json:"ui_locales" schema:"ui_locales"`
+	IDTokenHint  string              `json:"id_token_hint" schema:"id_token_hint"`
+	LoginHint    string              `json:"login_hint" schema:"login_hint"`
+	ACRValues    []string            `json:"acr_values" schema:"acr_values"`
 
-	Nonce       string              `schema:"nonce"`
-	Display     Display             `schema:"display"`
-	Prompt      SpaceDelimitedArray `schema:"prompt"`
-	MaxAge      *uint               `schema:"max_age"`
-	UILocales   Locales             `schema:"ui_locales"`
-	IDTokenHint string              `schema:"id_token_hint"`
-	LoginHint   string              `schema:"login_hint"`
-	ACRValues   []string            `schema:"acr_values"`
+	CodeChallenge       string              `json:"code_challenge" schema:"code_challenge"`
+	CodeChallengeMethod CodeChallengeMethod `json:"code_challenge_method" schema:"code_challenge_method"`
 
-	CodeChallenge       string              `schema:"code_challenge"`
-	CodeChallengeMethod CodeChallengeMethod `schema:"code_challenge_method"`
+	//RequestParam enables OIDC requests to be passed in a single, self-contained parameter (as JWT, called Request Object)
+	RequestParam string `schema:"request"`
 }
 
 //GetRedirectURI returns the redirect_uri value for the ErrAuthRequest interface