Services Edit UI: add fields for information needed by ToSback

[hugoroy]

@JimmStout Your contribution would be welcome here, can you explain to @pierreozoux (or anybody who wants to work on this) what fields are needed to have exploitable information to feed tosback?

See https://edit.tosdr.org/services/edit/GqwMKJqJNnHAymQnR for instance

[michielbdejong]

Instead of storing the "URLs", we could link to (in this example) https://github.com/tosdr/tosback2/blob/master/rules/github.com.xml

That ensures that tosdr.org and tosback.org data on document URLs is always in sync, which is good both for making sure tosback crawl rules get updated and for making sure tosdr reviews / links provided get updated. Also, it would be a first step towards linking the 'source' field of each data point to actually crawled document paragraphs.