Updated Header Extension Profile constants

[sirzooro]

Make Header Extension Profile constants public and added Cryptex ones.

Cryptex (RFC 9335) implementation in pion/srtp will need these constants.

[codecov]

Codecov Report

Attention: Patch coverage is 76.92308% with 3 lines in your changes missing coverage. Please review.

Project coverage is 86.87%. Comparing base (6469fef) to head (1d257f8).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
header_extension.go	0.00%	1 Missing and 2 partials ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #310   +/-   ##
=======================================
  Coverage   86.87%   86.87%           
=======================================
  Files          26       26           
  Lines        3108     3108           
=======================================
  Hits         2700     2700           
  Misses        350      350           
  Partials       58       58           

Flag	Coverage Δ
go	86.87% <76.92%> (ø)
wasm	86.32% <76.92%> (ø)

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[JoTurk]

Thanks