Handle empty arrays in -in and -between in subclasses

[jjatria]

Subclasses that override _where_field_IN and _where_field_BETWEEN and conditionally re-dispatch to the default handlers in SQL::Abstract were not correctly handling empty array references passed as arguments to -in, -between, and their negated counterparts.

This behaviour was broken in the refactor that lead to 2.000000, and more specifically in 1.90_03, going from

$ perl -Ilib -MSQL::Abstract -E '
  say "version " . $SQL::Abstract::VERSION;
  package X {
    use parent "SQL::Abstract";
    use mro "c3";
    sub _where_field_IN { shift->next::method(@_) }
  }
  say X->new->select( table => ["*"], { foo => { -in => [] } } )
'
version 1.9002
SELECT * FROM table WHERE 0=1

to

$ perl -Ilib -MSQL::Abstract -E '
  say "version " . $SQL::Abstract::VERSION;
  package X {
    use parent "SQL::Abstract";
    use mro "c3";
    sub _where_field_IN { shift->next::method(@_) }
  }
  say X->new->select( table => ["*"], { foo => { -in => [] } } )
'
version 1.9003
SELECT * FROM table WHERE foo IN ( )

and resulting in illegal SQL.

This was breaking behaviour that resulted in downstream issues affecting at least SQL::Abstract::More (see damil/SQL-Abstract-More#20).

Likewise, a class overriding _where_field_BETWEEN was not triggering the parameter validation that disallowed empty array references or undefined values to be used as parameters to -between and its negation:

$ perl -Ilib -MSQL::Abstract -E '
  say "version " . $SQL::Abstract::VERSION;
  package X {
    use parent "SQL::Abstract";
    use mro "c3";
    sub _where_field_BETWEEN { shift->next::method(@_) }
  }
  say X->new->select( table => ["*"], { foo => { -between => [] } } )
'
version 1.9003
SELECT * FROM table WHERE ( foo BETWEEN AND )

This change ensures that the path taken by subclasses that override those methods triggers equivalent code paths to those that don't.

Fixes https://rt.cpan.org/Ticket/Display.html?id=142341