Change plugin ID according to Grafana naming convention

[hagen1778]

Submitting plugin for signing throws an error: Organization Slug victorialogs used in this submission does not match the organization you are using. Our plugin ID is defined here and has value victorialogs-datasource.

Unfortunately, I wasn't able to find in Grafana docs info about naming convention for plugin ID. Except an old forum question here. According to it, the plugin ID should have the following form:

<grafana_cloud_username>-<plugin_name>-<plugin_type>

In our case, <grafana_cloud_username> is victoriametrics, <plugin_type> is datasource. So the convenient ID would be the following:

victoriametrics-victorialogs-datasource

Or to simplify it:

victoriametrics-logs-datasource

Changing plugin ID is a breaking change. Once changed, users will have to update their Grafana settings for unsigned plugin ID and re-install the plugin. The change and mitigation procedure should be outlined in update notes. Hopefully, once #127 is done those manipulations won't be needed anymore.

Alternative approach

Alternative approach would be to create a new Grafana org under victorialogs name. That would work as well, but this may result into further confusion for users as they would have to be aware of two orgs: victoriametrics and victorialogs.

[hagen1778]

Plugin ID was changed to victoriametrics-logs-datasource in https://github.com/VictoriaMetrics/victorialogs-datasource/releases/tag/v0.13.0