add means to automatically reconcile inv and wd editions sharing the same ISBN or another identifier

[maxlath]

As we now include wd editions (see #182 and #753), we have cases where a local edition entity will have an ISBN already used on Wikidata. Priority is given to local entities for now. As this is now all new, we have many such cases (~8000), but it will happen again in the future, if someone creates an edition on Inventaire and then someone else creates an edition on Wikidata with the same ISBN.

It's not a simple/classic merge:

• both the inv and the wd entity would have the same isbn prefixed uri
• the point was made that some work might have been put to making those editions data rich, and that we would at least need to auto-import claims when merging (which is currently not done, we only let users using the client manually select which claims should be copied over to Wikidata)

I was thinking that we could have a dedicated task module, like check-edition-duplicates that would be specialized in handling this types of cases:

function checkEditionDuplicates (uri: EntityUri) {
  // Get inv entity
  // Resolve wd entity by isbn or external id
  // If single match, check that no claim is in conflict
  //   In which case, transfer wd claims from inv entity to wikidata
  //   Turn inv entity into redirection or local layer to wikidata entity
  // Else, create task
}