Support loading plugins from the plugin Registry

from @jarben in Slack:
[here is an example](https://github.com/grafana/grafana-assistant-app/blob/5c24b5c259ea9583ca40e7ca0ea1078d6fe13eea/Tiltfile#L324) of the GF_INSTALL_PLUGINS using an url to the plugin zip file

[Tiltfile](https://github.com/grafana/grafana-assistant-app/blob/5c24b5c259ea9583ca40e7ca0ea1078d6fe13eea/Tiltfile)      

```
 'GF_INSTALL_PLUGINS': 'grafana-clickhouse-datasource,https://github.com/grafana/google-bigquery-datasource/releases/download/v2.1.0/grafana-bigquery-datasource-2.1.0.zip;grafana-bigquery-datasource,https://storage.googleapis.com/integration-artifacts/grafana-collector-app/release/latest/grafana-collector-app-latest.zip;grafana-collector-app',

```
> One issue is that we still need to add jsonData/secureJsonData to the apps.yml - this is not an issue when using repos directly, as they have testing plugin data we could fetch the data using gcom or HG API (for a given stack), HG also works with secureJsonData..

Start by reviewing the linked Tiltfile example and locating the corresponding apps.yml handling. Trace how plugin URLs and registry metadata are currently loaded, then determine how jsonData and secureJsonData should be sourced through gcom or the HG API. Done means registry plugins load with the required app configuration.

Written by the indexing model from the issue text.