Add support key specific rules.

[ls-cyril-grosset]

Hello, I would like to propose this change that allows the definition of rule set specific to one or more keys. This is helpful, if you want different quotas depending of the origin of the request for example.

[codecov]

Codecov Report

Merging #19 into master will increase coverage by 2.79%.
The diff coverage is 89.36%.

@@             Coverage Diff              @@
##             master      #19      +/-   ##
============================================
+ Coverage     63.33%   66.12%   +2.79%     
- Complexity      100      116      +16     
============================================
  Files            16       19       +3     
  Lines           330      369      +39     
  Branches         29       35       +6     
============================================
+ Hits            209      244      +35     
- Misses          114      115       +1     
- Partials          7       10       +3

Impacted Files	Coverage Δ	Complexity Δ
...ore/limiter/request/RequestLimitRulesSupplier.java	100% <100%> (ø)	8 <8> (?)
...iter/request/DefaultRequestLimitRulesSupplier.java	100% <100%> (ø)	3 <3> (?)
.../request/RedisSlidingWindowRequestRateLimiter.java	91.11% <100%> (-0.2%)	27 <0> (-1)
...elimitj/core/limiter/request/RequestLimitRule.java	73.52% <76.92%> (+0.45%)	16 <8> (+4)	⬆️
...s/request/SerializedRequestLimitRulesSupplier.java	83.33% <83.33%> (ø)	2 <2> (?)

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[mokies]

Thanks for the PR @cyril-grosset. I think this is a valuable addition and will attempt to merge