Plumb metric alias from query interface to DataflowPlanBuilder

This commit adds the necessary things to `MetricQueryParam` and to
the classes that build the query spec so that the alias information
reaches the `DataflowPlanBuilder`

metricflow-semantics/metricflow_semantics/protocols/query_parameter.py

@@ -22,6 +22,11 @@ def name(self) -> str:
         """The name of the metric."""
         raise NotImplementedError
 
+    @property
+    def alias(self) -> Optional[str]:
+        """The alias of the metric."""
+        raise NotImplementedError
+
     def query_resolver_input(  # noqa: D102
         self, semantic_manifest_lookup: SemanticManifestLookup
     ) -> ResolverInputForMetric:

metricflow-semantics/metricflow_semantics/query/query_resolver.py

@@ -14,6 +14,7 @@
 from metricflow_semantics.model.semantic_model_derivation import SemanticModelDerivation
 from metricflow_semantics.model.semantics.linkable_element_set import LinkableElementSet
 from metricflow_semantics.naming.metric_scheme import MetricNamingScheme
+from metricflow_semantics.protocols.query_parameter import MetricQueryParameter
 from metricflow_semantics.query.group_by_item.filter_spec_resolution.filter_pattern_factory import (
     WhereFilterPatternFactory,
 )
@@ -196,6 +197,18 @@ def _resolve_metric_inputs(
                     )
                 )
             else:
+                # Add the desired alias to the spec if it's provided in the input object
+                if (
+                    isinstance(metric_input.input_obj, MetricQueryParameter)
+                    and metric_input.input_obj.alias is not None
+                ):
+                    matching_specs = tuple(
+                        MetricSpec(
+                            element_name=ms.element_name,
+                            alias=metric_input.input_obj.alias,
+                        )
+                        for ms in matching_specs
+                    )
                 metric_specs.extend(matching_specs)
 
         return ResolveMetricsResult(

metricflow-semantics/metricflow_semantics/specs/query_param_implementations.py

@@ -128,6 +128,7 @@ class MetricParameter(ProtocolHint[MetricQueryParameter]):
     """Metric requested in a query."""
 
     name: str
+    alias: Optional[str] = None
 
     @override
     def _implements_protocol(self) -> MetricQueryParameter: