The code uses these checks in several places to know what to do with a
particular column, for instance AR attribute query methods has a branch
like this:

    if column.number?
      !value.zero?
    end

This should never be true for array columns, since it would be the same
as running [].zero?, which results in a NoMethodError exception.

Fixing this by ensuring that array columns in PostgreSQL never return
true for number?/text? checks.

Since most of the array support was based on the postgres_ext lib, it's
worth noting it does the same thing for numeric array columns too:

https://github.com/dockyard/postgres_ext/blob/v1.0.0/lib/postgres_ext/active_record/connection_adapters/postgres_adapter.rb#L72

This extended the same logic for text columns to ensure consistency.