add support for all django-filters RangeFilter

[juleswh]

Attempt to support all django-filters RangeFilters.

existing tests pass, I probably should make tests for some other cases.

I tried it on a project using DateFromToRangeFilter and it works as expected (with date_before and date_after query parameters)

[codecov]

Codecov Report

Merging #332 (7eefb2a) into master (aa13210) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #332   +/-   ##
=======================================
  Coverage   98.09%   98.09%           
=======================================
  Files          54       54           
  Lines        4945     4946    +1     
=======================================
+ Hits         4851     4852    +1     
  Misses         94       94           

Impacted Files	Coverage Δ
drf_spectacular/contrib/django_filters.py	87.36% <100.00%> (+0.13%)	⬆️

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[tfranzel]

thanks @juleswh! i just robustified this a little and added support for

class LookupChoiceWidget(SuffixedMultiWidget):
    suffixes = [None, 'lookup']

[juleswh]

Nice, thanks for taking it over!