Add header normalizer middleware

[dbartholomae]

Solves #9

[codecov]

Codecov Report

Merging #32 into master will not change coverage.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##            master       #32   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           27        29    +2     
  Lines          323       344   +21     
  Branches        64        66    +2     
=========================================
+ Hits           323       344   +21     

Impacted Files	Coverage Δ
...tp-header-normalizer/src/http-header-normalizer.ts	100.00% <100.00%> (ø)
packages/http-header-normalizer/src/logger.ts	100.00% <100.00%> (ø)

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