FU::Validate: Add module + integrate with FU

Copied from TUWF::Validate with a few small changes. I have a few more
features planned, but let's see how this goes first.

It's been an incredibly useful module in the past, I'm not sure right
now if I had ideas for potential improvements at some point, will need
to check notes.

c/common.c

@@ -189,6 +189,7 @@ static int fu_2bool(SV *val) {
         HV *stash = SvSTASH(rv);
         /* Historical: "JSON::XS::Boolean", not used by JSON::XS since 3.0 in 2013 */
         if (stash == gv_stashpvs("JSON::PP::Boolean", 0) /* Also covers Types::Serialiser::Boolean and used by a bunch of other modules */
+                || stash == gv_stashpvs("boolean", 0)
                 || stash == gv_stashpvs("Mojo::JSON::_Bool", 0)
                 || stash == gv_stashpvs("JSON::Tiny::_Bool", 0))
             return !!SvIV(rv);