feat(parse_header): provide our own implementation of parse_header()

[vytas7]

I have another branch which also introduces Cython's "pure Python mode" in order to speed up parse_header(), but we can circle back on that optimization in Falcon 4.1.

I'm also planning to reimplement the parts of mimeparse that we actually use, and unvendor it completely.

Fixes #2066

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (a78cfb3) to head (e209b20).

Additional details and impacted files

@@            Coverage Diff            @@
##            master     #2217   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           62        63    +1     
  Lines         6888      6930   +42     
  Branches      1099      1109   +10     
=========================================
+ Hits          6888      6930   +42     

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[CaselIT]

have just glanced at the mediatypes module since it's copied from the stdlib.

Did you make changes to it?

[vytas7]

have just glanced at the mediatypes module since it's copied from the stdlib.

Did you make changes to it?

@CaselIT yes, I wrote a much simpler implementation for the common case, and fall back to the old stdlib impl for more complex cases.

[CaselIT]

Ok, I'll take a better look later

[CaselIT]

looks ok but could maybe use one more test