Auth: Implement the SSO Settings List endpoint (#80769)

* add list endpoint & initial tests

* add tests and ETag

* format service_test.go

* add list swagger param, generate openAPI, remove ETag, use RedactedPassword

* correct swagger param name

* Align tests to latest changes

* use setting.RedactedValue()

* add string assertion

* lint & require no error on res.Body.Close()

* add custom response type

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Co-authored-by: Mihaly Gyongyosi <mgyongyosi@users.noreply.github.com>

pkg/setting/setting.go

@@ -602,6 +602,7 @@ func RedactedValue(key, value string) string {
 		"ACCOUNT_KEY",
 		"ENCRYPTION_KEY",
 		"VAULT_TOKEN",
+		"CLIENT_SECRET",
 	} {
 		if match, err := regexp.MatchString(pattern, uppercased); match && err == nil {
 			return RedactedPassword