Fix _build_extra_params to auto-encode deep objects

[SineSwiper]

Given that there are different kinds of searches, ones that are basic sets of variables and ones that are more complex JSON queries, the MetaCPAN::API::* methods should be able to adapt to both. To best solve this on the API.pm end, I added the extra logic to _build_extra_params to auto-convert deep objects to GET-encoded JSON with the source parameter.

This makes queries like this possible:

my $global_testing = $mcpan->release(
   search => {
      size   => 0,
      query  => { filtered => {
         query  => {match_all => {}},
         filter => { term => { distribution => $dist_name } },
      }},
      facets => {
         pass => { statistical => { field => 'tests.pass' } },
         fail => { statistical => { field => 'tests.fail' } },
      },
   }
);

Without the change, release passes it to fetch, fetch passes it to _build_extra_params, and _build_extra_params just dumbly encodes references as HASH(whatever) ref memory strings.

This is sort of a workaround, as the real solution would be some sort of fetch_or_post method that just does the right thing according to extra_params, if it's deep, and if it's nearing its 2000 character or so limit for query strings. However, having this logic here is still good as a DWIM measure, even if I did patch for that. (Which I probably will, when it's not 11:50PM :)

[xsawyerx]

This is good stuff!

[xsawyerx]

Merged, thanks! :)