feat: allow Qualifiers to match on spangroups

[Thomzoy]

Description

Proposition for allowing Qualifiers to look for matches in sentences present in doc.spans[key].
It would extend the current on_ents_only argument by adding another on_spangroups argument

Another way of doing this could be to be more general with, e.g. a on parameter that could be set to tell the Qualifiers to match on

• everything
• all entities
• entities present in spangroups
• entities present in a subset of spangoups

However, this approach would induce many API breaking changes, so maybe the first approach is preferable

Checklist

• If this PR is a bug fix, the bug is documented in the test suite.
• Changes were documented in the changelog (pending section).
• If necessary, changes were made to the documentation (eg new pipeline).

[Thomzoy]

Actualy some work was already done in the dates pipelines, so I took some inspiration from it

[percevalw]

Closing as this was merged in #213