feat: App API v2 (#10077)

# Which Problems Are Solved

This PR *partially* addresses #9450 . Specifically, it implements the
resource based API for the apps. APIs for app keys ARE not part of this
PR.

# How the Problems Are Solved

- `CreateApplication`, `PatchApplication` (update) and
`RegenerateClientSecret` endpoints are now unique for all app types:
API, SAML and OIDC apps.
  - All new endpoints have integration tests
  - All new endpoints are using permission checks V2

# Additional Changes

- The `ListApplications` endpoint allows to do sorting (see protobuf for
details) and filtering by app type (see protobuf).
- SAML and OIDC update endpoint can now receive requests for partial
updates

# Additional Context

Partially addresses #9450

internal/domain/application_saml.go

@@ -11,9 +11,9 @@ type SAMLApp struct {
 	AppName      string
 	EntityID     string
 	Metadata     []byte
-	MetadataURL  string
-	LoginVersion LoginVersion
-	LoginBaseURI string
+	MetadataURL  *string
+	LoginVersion *LoginVersion
+	LoginBaseURI *string
 
 	State AppState
 }
@@ -31,11 +31,14 @@ func (a *SAMLApp) GetMetadata() []byte {
 }
 
 func (a *SAMLApp) GetMetadataURL() string {
-	return a.MetadataURL
+	if a.MetadataURL != nil {
+		return *a.MetadataURL
+	}
+	return ""
 }
 
 func (a *SAMLApp) IsValid() bool {
-	if a.MetadataURL == "" && a.Metadata == nil {
+	if (a.MetadataURL == nil || *a.MetadataURL == "") && a.Metadata == nil {
 		return false
 	}
 	return true