[receiver/snowflake] add metrics (open-telemetry#15296)

Define metrics in metadata.yaml and ran mdatagen to create the metadata package for use in receiver component. Metrics are designed for parity with existing smartagent. Dimensions have been translated into attributes with the same column values associated. The smartagent definition does not include data types so care was taken to apply applicable types to each metric and attribute field.

.chloggen/snowflake_add_metrics.yaml

@@ -0,0 +1,16 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: snowflakereceiver
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: added metrics to snowflakereceiver
+
+# One or more tracking issues related to the change
+issues: [14754]
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext: generated w/ mdatagen