Allow tagged-any & tagged-all to be used in where exprs

This change allows the single tag form of tagged-any &
tagged-all to be used in a where predicate expression.

Previously where-rewrite would only recognize tagged.
The logic for all three forms is the same in this case
because it only checks for the existence of a single tag.
Update the docs for tagged-* & where about test exprs

Note that tagged-any & tagged-all can be used in where
test expressions, but only the single tag form.

Testing for a collection of tags is not supported yet.
Merge pull request #227 from samn/where-tagged-rewrite

Allow tagged-any & tagged-all to be used in where exprs