(EAI-152) check for change to chunkAlgoHash when updating embeddings

[yakubova92]

Jira: https://jira.mongodb.org/browse/EAI-152

Changes

• Previously, updateEmbeddedContent would re-chunk if the page content changed OR chunkAlgoHash changed since the date provided
• Now, it updates embedded content when the chunk algo has changed, even if there were no other changes to the page, essentially ignoring the since date provided

[mongodben]

see comment about caching.

and beyond that, sorry if i'm dense, but what changes are you making?

[mongodben]

see comment about the $lookup implementation

[mongodben]

see comment about typing

[nlarew]

A few small suggested tweaks + one question about the caching behavior