Add support for default exclusion of $vector and $vectorize

[tatu-at-datastax]

What this PR does:

Will change default projection inclusion to exclude $vector and $vectorize, needing explicit inclusion.

Which issue(s) this PR fixes:
Fixes #1005

Checklist

• Changes manually tested
• Automated Tests added/updated
• Documentation added/updated
• CLA Signed: DataStax CLA

[tatu-at-datastax]

Caller will use the short-cut, no need to check whether explicit definition happens to work like default projection.

[tatu-at-datastax]

Simplifying the test since $vector not really needed for test (but new default projection would drop)

[vkarpov15]

LGTM so far

[Yuqi-Du]

This is interesting.
So by default, idInclusion will be null, which will give addDocId as

• true for inclusion-based projection
• false for exclusion-based projection

So essentially the meaning of addDocId will be flipped, in terms of what projection is used inclusion-based or exclusion-based. The variable name addDocId (similarly add$vector, add$vectorize) gives some confusion to me initially, but it makes sense afterwards.

[tatu-at-datastax]

Good point, naming is hard. Instead of "addDocId" could use "includeDocId" but that would be even more confusing.
If you (or anyone else) has better name suggestion would be happy to rename.

[Yuqi-Du]

if we understand correctly,
"projection": {"name" : true, "age":false} will error out, since projection logic thinks this is inclusion-based
but since $vector and $vectorize are special cases and handled differently(not by List paths), so we still allow something like this ?
"projection": { "$vector": 1, "$vectorize" : 0}

[tatu-at-datastax]

if we understand correctly, "projection": {"name" : true, "age":false} will error out, since projection logic thinks this is inclusion-based but since $vector and $vectorize are special cases and handled differently(not by List paths), so we still allow something like this ? "projection": { "$vector": 1, "$vectorize" : 0}

Correct: _id, $vector, $vectorize (and any future $-prefixed special fields) are special in that they can be used for any inclusion/exclusion case.