feat: implement query_metrics

query_metrics currently has no implementation, meaning once a metric is emitted there is no way in llama stack to query it from the store.

implement query_metrics for the meta_reference provider which follows a similar style to `query_traces`, using the trace_store to format an SQL query and execute it

in this case the parameters for the query are `metric.METRIC_NAME, start_time, and end_time`.

this required client side changes since the client had no `query_metrics` or any associated resources, so any tests here will fail but I will provider manual execution logs for the new tests I am adding

order the metrics by timestamp.

Additionally add `unit` to the `MetricDataPoint` class since this adds much more context to the metric being queried.

these metrics can also be aggregated via a `granularity` parameter. This was pre-defined as a string like: `1m, 1h, 1d` where metrics occuring in same timespan specified are aggregated together.

Signed-off-by: Charlie Doern <cdoern@redhat.com>

docs/_static/llama-stack-spec.html

@@ -16067,12 +16067,16 @@
                     "value": {
                         "type": "number",
                         "description": "The numeric value of the metric at this timestamp"
+                    },
+                    "unit": {
+                        "type": "string"
                     }
                 },
                 "additionalProperties": false,
                 "required": [
                     "timestamp",
-                    "value"
+                    "value",
+                    "unit"
                 ],
                 "title": "MetricDataPoint",
                 "description": "A single data point in a metric time series."

docs/_static/llama-stack-spec.yaml

@@ -11954,10 +11954,13 @@ components:
           type: number
           description: >-
             The numeric value of the metric at this timestamp
+        unit:
+          type: string
       additionalProperties: false
       required:
         - timestamp
         - value
+        - unit
       title: MetricDataPoint
       description: >-
         A single data point in a metric time series.