Auth: Implement the SSO Settings GET endpoint (#79144)

* Return data in camelCase from the OAuth fb strategy

* changes

* wip

* Add defaults for oauth fb strategy

* revert other changes

* basic includeDefaults query param implementation

* basic secret removal and etag implementation

* correct imports

* rebase

* move default settings filter to models

* only replace ClientSecret value if set

* first GetForProvider test & use FNV for ETag to avoid Blocklisted import error

* add tests

* add annotation for the openapi spec & generate spec

* remove TODO

* use IsSecret, improve tests, remove DefaultOAuthSettings

* add comment explaining generateFNVETag

* add error handling for generateFNVETag

* run go generate

* Update pkg/services/ssosettings/api/api.go

Co-authored-by: Mihai Doarna <mihai.doarna@grafana.com>

* move isSecret to service, create GetForProviderWithRedactedSecrets func

* add unit test for GetForProviderWithRedactedSecrets & remove duplicated code

* regen openapi/swagger

* revert dependency bumps

---------

Co-authored-by: Mihaly Gyongyosi <mgyongyosi@users.noreply.github.com>
Co-authored-by: Mihai Doarna <mihai.doarna@grafana.com>

pkg/services/ssosettings/models/models.go

@@ -26,6 +26,23 @@ func (s SettingsSource) MarshalJSON() ([]byte, error) {
 	}
 }
 
+func (s *SettingsSource) UnmarshalJSON(data []byte) error {
+	var source string
+	if err := json.Unmarshal(data, &source); err != nil {
+		return err
+	}
+
+	switch source {
+	case "database":
+		*s = DB
+	case "system":
+		*s = System
+	default:
+		return fmt.Errorf("unknown source: %s", source)
+	}
+	return nil
+}
+
 type SSOSettings struct {
 	ID        string         `xorm:"id pk" json:"id"`
 	Provider  string         `xorm:"provider" json:"provider"`