Feature Request - var interpolation inside of query()

When creating a template, it'd be really handy to be able to pass in a relevant string that varies between tasks vs having to pass the entire query into the var

```
var thingName string
var crit lambda

batch
|query('''
SELECT mean("value")
FROM "myDB"."autogen".foo
WHERE "thing" = {{ thingName }}
''')
...
|alert()
.crit(crit)
...
```

Start by tracing how query() templates handle variables and how the example's thingName and crit values are resolved. Define the interpolation behavior and verify that task-specific values can be supplied without passing the entire query through a variable.

Written by the indexing model from the issue text.