refactor: encryption envelope APIs, tests

[Patrik-Stas]

• Builds on top of fix: didcomm message forwarding #1081 - please merge that first
• Restores (and simplifies) tests of EncryptionEnvelope
• Refactors EncryptionEnvelope by decoupling its APIs from concept of Aries messages. Even inherently didcomm !== aries, so this decoupling makes broader sense and also makes testing a lot easier.
  • The changes also represent one step towards dropping usage of legacy AriesDidDoc structure in encryption envelope
• Deleted unused error mappings

[codecov-commenter]

Codecov Report

Attention: 181 lines in your changes are missing coverage. Please review.

Comparison is base (a7bac93) 0.05% compared to head (5fc1905) 0.05%.

❗ Current head 5fc1905 differs from pull request most recent head a00160a. Consider uploading reports for the commit a00160a to get more accurate results

Files	Patch %	Lines
aries/aries_vcx/src/utils/encryption_envelope.rs	0.00%	161 Missing ⚠️
aries/aries_vcx_core/src/wallet/indy/signing.rs	0.00%	11 Missing ⚠️
...ries/aries_vcx_core/src/wallet/indy/indy_wallet.rs	0.00%	8 Missing ⚠️
aries/aries_vcx/tests/test_connection.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##            main   #1082      +/-   ##
========================================
- Coverage   0.05%   0.05%   -0.01%     
========================================
  Files        471     471              
  Lines      24019   24093      +74     
  Branches    4295    4332      +37     
========================================
  Hits          13      13              
- Misses     24005   24079      +74     
  Partials       1       1              

Flag	Coverage Δ
unittests-aries-vcx	0.05% <0.00%> (-0.01%)	⬇️

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[xprazak2]

Just a couple of nitpicks , looks ok to me.

[xprazak2]

Needs a rebase 🥲

[Patrik-Stas]

@xprazak2 rebased

[xprazak2]

Thanks!