feat: add otx tracking API, add enums, minor fixes

* otx can nw be tracked at /api/track/:trackingId
* moved queries to queries folder
* fixed validation error check in ErrorHandler
* added enum package with enum types
* updated migrations: added enum tables

pkg/enum/enum.go

@@ -0,0 +1,27 @@
+package enum
+
+type (
+	// OtxStatus represents enum-like values received in the dispatcher from the RPC node or Network callback.
+	// It includes a subset of well-known and likely failures the dispatcher may encounter.
+	OtxStatus string
+	// OtxType reprsents the specific type of signed transaction.
+	OtxType string
+)
+
+// NOTE: These values must also be inserted/updated into db to enforce referential integrity.
+const (
+	IN_NETWORK             OtxStatus = "IN_NETWORK"
+	OBSOLETE               OtxStatus = "OBSOLETE"
+	SUCCESS                OtxStatus = "SUCCESS"
+	FAIL_NO_GAS            OtxStatus = "FAIL_NO_GAS"
+	FAIL_LOW_NONCE         OtxStatus = "FAIL_LOW_NONCE"
+	FAIL_LOW_GAS_PRICE     OtxStatus = "FAIL_LOW_GAS_PRICE"
+	FAIL_UNKNOWN_RPC_ERROR OtxStatus = "FAIL_UNKNOWN_RPC_ERROR"
+	REVERTED               OtxStatus = "REVERTED"
+
+	GIFT_GAS         OtxType = "GIFT_GAS"
+	ACCOUNT_REGISTER OtxType = "ACCOUNT_REGISTER"
+	GIFT_VOUCHER     OtxType = "GIFT_VOUCHER"
+	REFILL_GAS       OtxType = "REFILL_GAS"
+	TRANSFER_VOUCHER OtxType = "TRANSFER_VOUCHER"
+)