Add api.content.get_parents

[davisagli]

It would be nice to provide an API for iterating through all of an object's parents. It can be implemented using Acquisition.aq_chain

Nice to have: Provide a way to filter the parents for ones that implement a particular interface or match a predicate. Provide a way to get the closest parent that matches these filters (if any).

[yurj]

https://community.plone.org/t/best-way-to-get-the-object-parent/19633

here some ideas and discussion. In particular we could add an option to get the parent with or without aq_inner.

[ale-rt]

I think it should rather be api.content.get_ancestors, at least other libraries to that:

• https://lxml.de/api/lxml.etree.AncestorsIterator-class.html
• https://networkx.org/documentation/stable/reference/algorithms/generated/networkx.algorithms.dag.ancestors.html

[ale-rt]

I consider this something interesting to have in plone.restapi.

For me the function signature should be:

def iter_ancestors(obj, function=None, interface=None):

In that case the closest one can be fetched with:

next(iter_ancestors(obj, ...), None)

[ale-rt]

I implemented that concept on top of what @rohnsha0 did, see #562 if that makes sense to you.