[Task]: Make configuration of NARC scanner rules possible immediately at creation

[diox]

Description

mozilla/addons-server#24388 added the ability to configure NARC rules, but there is a known limitation at the moment: the configuration is only available when addons-server "knows" what scanner the rule is for, so on the creation UI, the configuration bits don't show up, you need to submit the form first.

We should dynamically show the relevant configuration according to the scanner being selected, through some JavaScript + an endpoint that would return the default config schema and re-trigger the jsonform widget init

Acceptance Criteria

• item 1

┆Issue is synchronized with this Jira Task