Generate url with nested query params

[snewcomer]

ref emberjs/ember.js#19791

Bug

Nested query params are not serialized into the URL property

/?filter=%5Bobject%20Object%5D

Expected

/?filter=[user][name][$contains]=nick

There are some other considerations - generating nested query strings can be done many different ways and exploring a solution requires that we settle on "one" of the ways to ensure we don't go breaking users.

e.g. a nested filter

?filter[make]=honda&filter[model]=civic
?filter=[make]=honda&filter=[model]=civic
?filter.make=honda&filter.model=civic

e.g. nested array filter
?a[0]=b&a[1]=c
?a[]=b&a[]=c
?a=b&a=c

Note - libraries like qs have taken stances on certain patterns. We can glean what to do from them but in no means is it the "correct" way.