Allow U&P rate limiter's config to be overridden for specific routes

[WalkingPizza]

What does it do?

It overrides the default U&P rate limiter settings when a config is specified for the middleware at a specific route.

Why is it needed?

Currently, there is no way to change the rate limiting criteria for U&P routes on a per-route basis. You either keep the defaults or change those defaults for all routes, but you can't set specific requirements just for certain routes – eg. those that send emails.

How to test it?

Try overriding the rate limiter's config either through a direct extension of the U&P plugin or through the register function.

[derrickmehaffy]

LGTM

[codecov]

Codecov Report

Merging #12375 (bf87b56) into master (7b4d0e0) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master   #12375   +/-   ##
=======================================
  Coverage   47.59%   47.59%           
=======================================
  Files         228      228           
  Lines        8527     8527           
  Branches     1904     1904           
=======================================
  Hits         4058     4058           
  Misses       3674     3674           
  Partials      795      795           

Flag	Coverage Δ
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unit	47.59% <ø> (ø)

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