OData support for $select

[mgroves]

A question came in from Stack Overflow on OData with Linq2Couchbase: https://stackoverflow.com/questions/61078681/how-to-apply-odata-select-after-couchbase-iqueryable-is-executed

A minimum source code to reproduce the issue is here: https://github.com/ofthelit/ODataCouchbase

It looks like $select causes a NotImplementedException. I ran the code, and found that the N1QL itself is generated correctly and executes correctly. But in BucketQueryExecutor.cs, ExecuteCollection, running the query results in the exception. Supporting a $select seems like a common scenario in OData. Is this a bug, or is this just not yet supported? What would it take to get it supported?

(See also issue #222)

[brantburnett]

@mgroves Frankly, my hope is that an EF Core 3 provider will address most of the problems. When I looked into it previously, the OData lambdas were especially complicated. I believe that EF Core would handle most of that complexity for us, without reinventing the wheel.

That said, it's possible that some of the simpler cases like select might be supportable. We'd have to see.

Also, the problem might be this: #134 (comment)