Feature: Support all macros in Variable query editor

[brycefisher]

Context

• Grafana v6.3.5 (67bad72)
• Azure Data Explorer Datasource version 2.0.0

What is Working

When creating a Variable for a dashboard, the $__from and $__to macros seem to expand into values from the timepicker as expected. Hooray! Example broken query showing expansion:

$__from .. $__to

What's Not Working

When trying to use these macros, the expected expansion does not occur:

• $__timeFilter() --> timestamp between (datetime(<from>) .. datetime(<to>))
• $__timeFrom --> datetime(<from>)
• $__timeTo --> datetime(<to>)

Examples:

$__timeFilter

---

$__timeFrom and $__timeTo

---

Requested Change

I'd love to see the queries written inside Variable section expand as they do for queries written inside Panels (spelled out succintly here: https://github.com/grafana/azure-data-explorer-datasource/releases/tag/v2.0.0)

Why this is a problem

• "Bad" surprise -- users can't use the existing macro from Panels in template variables, but both feel like the same kind of thing
• Hard to read -- because the query is only a single line and coercing a value from unix timestamp to Kusto datetime might take up a lot of that line, the query itself gets hard to read and easy to mess up

[srclosson]

Well defined, and a useful feature that other plugins support (ie: postgres).

Moving this into the backlog.

[vickyyyyyyy]

related to this #288

[andresmgot]

We can revamp the variable editor and re use the same than in dashboards like we do in other data sources. With that, macros should work out of the box.