Support the comparison of String and LocalDate

[chipkent]

For backwards compatibility reasons, it is desirable to be able to directly compare String and LocalDate objects. There is potential overhead from doing this, but the overhead was determined to be acceptable for not breaking compatibility.

For example:

from deephaven import empty_table

t = empty_table(1).update([
    "X = '2021-01-13'",
    "Y = new String[]{`2021-01-12`,`2021-01-13`,`2021-01-14`}"
]).ungroup()

t2 = t.where("X > Y")

[rcaudy]

This is exactly the kind of change I had in mind. It needs to go through io.deephaven.engine.table.impl.lang.QueryLanguageFunctionGenerator however.

[chipkent]

I believe the final decision was to not make conversions.