Plugin E2E: Add support for testing alert query

[sunker]

What this PR does / why we need it:

This PR makes it possible to write e2e tests that verifies that a backend data source plugin can return data frames in a format that is compatible with alerting.

The process for testing alerting compatibility is as follows:

1. Use alertRuleEditPage fixture to open a new, empty alert rule edit page OR use the gotoAlertRuleEditPage fixture to open an already existing alert rule.
2. Get query editor row, set data source and fill in the query
3. Click the Preview button to evaluate the alert query. If successful, the data source is compatible with alerting.

This AlertRuleEditPage model follows the same pattern as all the other page models - it can be instantiated with or without an id. As mentioned above, it's exposed through alertRuleEditPage fixture (new alert rules) and gotoAlertRuleEditPage fixture (existing alert rules). I've also added a readProvisionedAlertRule that makes it possible to read a provisioned alert rule.

In practice, I think this will be useful to check for regressions in backend data source plugins. In the past, it has happened that changes to the backend code and how the data frames are being constructed leads to breakages in alerting. Running e2e tests that checks for breakages should be able to catch these regressions.

Which issue(s) this PR fixes:

Part of #796

Will follow up with a docs PR later.

📦 Published PR as canary version: Canary Versions

✨ Test out this PR locally via:

npm install @grafana/[email protected]
# or 
yarn add @grafana/[email protected]

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[mckn]

I think this looks great!

I think the flows are a bit different if you are defining the alert rules as Grafana managed and Datasource managed alert rules. But I guess it should be enough to test the datasource via the Grafana managed flow.

[sunker]

@josmperez do you want to have a look at the docs?

[josmperez]

ignore approval (added it to wrong PR). i will review soon.

[CLAassistant]

All committers have signed the CLA.

[sunker]

@josmperez can you take a look at the docs?

[josmperez]

Nice work. LGTM.

[grafana-plugins-platform-bot]

🚀 PR was released in @grafana/[email protected] 🚀