AzureMonitor: Support decimal (as float64) type in analytics/logs (#28480)

loss of precision but will make the response work instead of erroring
follows work already done in the ADX plugin
fixes #28278

pkg/tsdb/azuremonitor/testdata/loganalytics/7-log-analytics-all-types-table.json

@@ -38,6 +38,10 @@
           {
             "name": "XTimeSpan",
             "type": "timespan"
+          },
+          {
+            "name":"XDecimal",
+            "type":"decimal"
           }
         ],
         "rows": [
@@ -50,10 +54,11 @@
             2147483647,
             9223372036854775807,
             1.7976931348623157e+308,
-            "00:00:00.0000001"
+            "00:00:00.0000001",
+            "79228162514264337593543950335"
           ]
         ]
       }
     ]
   }
-  
+