Update mongo libs from 3.6 to 5

[bewest]

Revert a revert to get original pull request back.
This reverts commit 2e65b1d. Try to bring back #8026.

[bewest]

@MilosKozak Does AAPS send multiple batch items through this interface? If so, it looks like the websocket stuff may still need more work.

[bewest]

There is a list of methods targeted here:
https://github.com/mongodb/node-mongodb-native/blob/HEAD/etc/notes/CHANGES_5.0.0.md

Here's an especially relevant section:

Collection.insert, Collection.update, and Collection.remove removed

Three legacy operation helpers on the collection class have been removed:

Removed API	API to migrate to
insert(document)	insertOne(document)
insert(arrayOfDocuments)	insertMany(arrayOfDocuments)
update(filter)	updateMany(filter)
remove(filter)	deleteMany(filter)

The insert method accepted an array of documents for multi-document inserts and a single document for single-document inserts. insertOne should now be used for single-document inserts and insertMany should be used for multi-document inserts.

I've completed a review of the source tree and and have converted all insert calls into insertOne. If AAPS or something else uses this to modify multiple activities, foods, profiles, or calls dbAdd via websocket with multiple documents, there will probably be issues. Also it's not clear what users are doing with the results from websocket events given to the callback.

Also, for whatever reason, remove(filter) seems to still work...
Tests have been added for areas of the api that were missing.

We need some actual testing with AAPS rigs (different/older versions would be nice as well), multiple looping systems, etc.

Another significant thing to note is that there is now a 15 second delay between entering data and seeing it reappear on the display, likely due to debouncing. We can adjust this based on feedback.

[bewest]

AAPS folks: do multiple documents come through this interface as an array? Can you provide any examples?

[adamlounds]

Do you have a roadmap or anything around browser support? How much longer will the codebase use var instead of let/const?

Looks like any android/ios device since 2011 should support let/const - there are no vendor-currently-supported os/browser combinations that don't support them.

Maybe the approach could be "use nightscout 15 for old browsers" and do any work on the f/e to support newer testing/frameworks in a nightscout v16 that will only support newer browsers? I think you'll rapidly paint yourself into a corner if "we're not waiting" becomes "we support your ancient devices forever"