Converter: Add support for parsing prometheus string (#48727)

pkg/util/converter/testdata/prom-string-frame.json

@@ -0,0 +1,40 @@
+{
+  "frames": [
+    {
+      "schema": {
+        "meta": {
+          "type": "timeseries-many"
+        },
+        "fields": [
+          {
+            "name": "Time",
+            "type": "time",
+            "typeInfo": {
+              "frame": "time.Time"
+            }
+          },
+          {
+            "name": "Value",
+            "type": "string",
+            "typeInfo": {
+              "frame": "string"
+            },
+            "labels": {
+              
+            }
+          }
+        ]
+      },
+      "data": {
+        "values": [
+          [
+            1651680139104
+          ],
+          [
+            "example"
+          ]
+        ]
+      }
+    }
+  ]
+}

pkg/util/converter/testdata/prom-string-golden.txt

@@ -0,0 +1,18 @@
+🌟 This was machine generated.  Do not edit. 🌟
+
+Frame[0] {
+    "type": "timeseries-many"
+}
+Name: 
+Dimensions: 2 Fields by 1 Rows
++-----------------------------------+----------------+
+| Name: Time                        | Name: Value    |
+| Labels:                           | Labels:        |
+| Type: []time.Time                 | Type: []string |
++-----------------------------------+----------------+
+| 2022-05-04 16:02:19.104 +0000 UTC | example        |
++-----------------------------------+----------------+
+
+
+====== TEST DATA RESPONSE (arrow base64) ======
+FRAME=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

pkg/util/converter/testdata/prom-string.json

@@ -0,0 +1,10 @@
+{
+	"status": "success",
+	"data": {
+		"resultType": "string",
+		"result": [
+			1651680139.104,
+			"example"
+		]
+	}
+}