[APP-183] feat: secondary time column selection on explore

[briangregoryholmes]

Checklist:

• [ ] Covered by tests
• [ ] Ran it and it works as intended
• [ ] Reviewed the diff before requesting a review
• [ ] Checked for unhandled edge cases
• [ ] Linked the issues it closes
• [ ] Checked if the docs need to be updated. If so, create a separate Linear DOCS issue
• [ ] Intend to cherry-pick into the release branch
• [ ] I'm proud of this work!

[ericpgreen2]

I believe I missed the demo of this feature when I was OOO, so I'm a little out-of-the-loop. What's the status on this?

[briangregoryholmes]

This is ready. Just need #7779 and #7857 to merge first.

[bito-code-review[bot]]

The suggestion is to rename the newly added time_column field to time_dimension for consistency with existing terminology. Looking at the ExplorePreset struct, there are already fields like dimensions and comparison_dimension that use the "dimension" terminology to represent aggregatable fields in the metrics layer, which may not correspond to actual database table columns.

proto/gen/rill/runtime/v1/resources.pb.go

// Current addition:
+	TimeColumn      *string `protobuf:"bytes,33,opt,name=time_column,json=timeColumn,proto3,oneof" json:"time_column,omitempty"`

// Should be renamed to:
+	TimeDimension   *string `protobuf:"bytes,33,opt,name=time_dimension,json=timeDimension,proto3,oneof" json:"time_dimension,omitempty"`