[release] 1.19.0 - Standardize persisted evaluation schema (#164)

* Updated schema of persisted storage data to be standardized across
SDKs
* Added group name to layers
* Updated diagnostics for ID lists
* Fixed issue with writing ID lists in incorrect order to data adapter





>Included In This Release
>- 21b0eaf sroyal-statsig
>   - Layer Group Name (#163)
>- d152dd8 kenny-statsig
>   - [EE-274] standardize evaluation json schema (#162)
>- c33c6ec kenny-statsig
>   - make writing id list to data store thread safe (#161)
>- 9820772 kenny-statsig
>   - update diagnostics (#158)
>- 1cb6933 kenny-statsig
>   - fix test flakiness (#160)
>- 031e79c kenny-statsig
>   - add language version to header and handle nil body (#159)

statsig_metadata.go

@@ -14,7 +14,7 @@ type statsigMetadata struct {
 func getStatsigMetadata() statsigMetadata {
 	return statsigMetadata{
 		SDKType:         "go-sdk",
-		SDKVersion:      "1.18.0",
+		SDKVersion:      "1.19.0",
 		LanguageVersion: runtime.Version()[2:],
 		SessionID:       SessionID(),
 	}