Add initial JSON formatter

It works and can format all "plain" Perl data, but has a few known bugs
and limitations that still need to be worked out.

It's about 8x smaller than JSON::XS's encoder and *much* smaller than
Cpanel::JSON::XS, but this is just a first attempt, it'll grow.

FU/Util.pm

@@ -0,0 +1,17 @@
+package FU::Util 0.1;
+
+use v5.36;
+use FU::XS;
+use Exporter 'import';
+
+our @EXPORT_OK = qw/json_format/;
+
+
+sub json_format($val, %opt) {
+    my $r = FU::XS::json_format($val);
+    # XXX: Does this go over the bytes? If so, not setting SvUTF8_on() in the first place would be much faster.
+    utf8::encode($r) if $opt{utf8};
+    $r
+}
+
+1;