Series import: make it possible to re-run every stage again

[php-coder]

The issue is similar to #1254 but for every stage. When we add a new locator or improve/fix extractors, we should be able to re-run import process and extract more data. When it was re-run that way it should stop on every stage and don't proceed automatically as with a normal import flow.

• Split the parsing and extraction stages #1358: Split the parsing and extraction stages
• Allow to re-run parsing stage
• Allow to re-run extraction stage
• Allow to add newly extracted data into a series