vam: Array Expressions

[mattnibs]

Add vector array expressions. When building an array in vector land you are often creating a non-union inner type that includes values from multiple vectors. This presents a problem because you cannot merge the vectors using a dynamic because dynamics are supposed to bubble up on be on top. As such I've added vector.Builder that is used to rebuild the multiple vectors to a single vector when this is encountered.

[philrz]

I happened to be revisiting the mgbench queries and since I get vector expression type *dag.ArrayExpr: not supported on the tip of main when trying to run bench1/q1 with vectors, I remembered this branch just went up. I now get:

$ super -version
Version: v1.18.0-139-ge69d3fd6

$ super dev vector query "where
     log_time >= 2017-01-11T00:00:00Z
     and machine_name in ['anansi','aragog','urd']" bench1.csup

invalid binary operator in

Not sure if that's expected to work here or would come later, but figured I'd report.

[mattnibs]

@philrz no support for in operator in this pr

[nwt]

Also change sequential array spreads so that spreads on non-array values yield the value itself.

What about docs? And record spreads on non-record values?

[mattnibs]

@nwt can we handle records in a separate pr?

[mattnibs]

Given there's some controversy over this I'm just going to get rid of spread on primitives for now

[mattnibs]

@nwt ready for another review I added back the behavior where non-spreadable elements are ignored.