Adds support for AEAD_AES_256_GCM

[digitalix]

Description

This adds support for AEAD_AES_256_GCM in srtp module. Later webrtc itself will have to be updated as well to enable support for AEAD_AES_256_GCM fully.

[codecov]

Codecov Report

Patch coverage: 87.50% and project coverage change: +0.03 🎉

Comparison is base (32e385b) 76.50% compared to head (b2d8f18) 76.54%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #238      +/-   ##
==========================================
+ Coverage   76.50%   76.54%   +0.03%     
==========================================
  Files          17       17              
  Lines        1243     1245       +2     
==========================================
+ Hits          951      953       +2     
  Misses        200      200              
  Partials       92       92              

Flag	Coverage Δ
go	76.54% <87.50%> (+0.03%)	⬆️
wasm	76.06% <87.50%> (+0.03%)	⬆️

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Impacted Files	Coverage Δ
protection_profile.go	80.00% <85.71%> (+0.83%)	⬆️
context.go	88.61% <100.00%> (ø)

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[Sean-Der]

LGTM! Great to see you contributing again @digitalix

[Sean-Der]

@at-wat @stv0g What do you think about removing the go.mod bumping. Maybe I am missing the value add?

Users on old versions of Go will think they can’t use these libraries. We aren’t using any new Go features though so no reason to block them?

Sorry If I am missing the benefit. Just want Pion to work for most people possible

[stv0g]

My motivation for this check has been mainly harmonization between the various Pion modules.
In my opinion, we should also set clear expectations about which Go versions are supported.
Currently, we are only testing Go 1.19 and 1.20 which matches Go's support policy.
Hamonizing the go.mod version also clearly states which language features and standard packages we are allowed to use.
Currently, we have largely varying versions in the different modules which makes it hard to grasp which features we can use.