DNM: Proof of concept of using our own ED25519 keys

[amaury1093]

Description

• create our own proto type ED25519
• Inner Key field is []byte
• Copy ed25519 files from Tendermint
• implement crypto.PubKey on the proto struct

Workarounds added:

• We register, in Amino, both TM's ed25519 and our own proto ed25519
• Added a AsTmPubKey() method on the proto type, to convert our own ed25519 into TM's ed25519. Where TM expects a TM ed25519 (e.g. the tmtypes.NewValidator() function), we need to make sure to pass in pubkey.AsTmPubKey()
• Added a workaround for bech32ifying ed25519 keys.

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• Targeted PR against correct branch (see CONTRIBUTING.md)
• Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
• Code follows the module structure standards.
• Wrote unit and integration tests
• Updated relevant documentation (docs/) or specification (x/<module>/spec/)
• Added relevant godoc comments.
• Added a relevant changelog entry to the Unreleased section in CHANGELOG.md
• Re-reviewed Files changed in the Github PR explorer
• Review Codecov Report in the comment section below once CI passes

[codecov]

Codecov Report

Merging #7343 into marie/6928-baseacc-pk will decrease coverage by 0.65%.
The diff coverage is 25.00%.

@@                    Coverage Diff                    @@
##           marie/6928-baseacc-pk    #7343      +/-   ##
=========================================================
- Coverage                  58.07%   57.41%   -0.66%     
=========================================================
  Files                        461      421      -40     
  Lines                      30820    26032    -4788     
=========================================================
- Hits                       17898    14947    -2951     
+ Misses                     11359     9652    -1707     
+ Partials                    1563     1433     -130