[issue-#1389] add multisig tx support

[GAtom22]

Closes: #1389

Description

Added required logic to support multi-signature transactions using ethsecp256k1.PubKey public keys

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For contributor use:

• 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

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For admin use:

• Added appropriate labels to PR (ex. WIP, R4R, docs, etc)
• Reviewers assigned
• Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)

[codecov]

Codecov Report

Merging #1390 (a527b05) into main (83e509b) will increase coverage by 0.03%.
The diff coverage is 73.33%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1390      +/-   ##
==========================================
+ Coverage   56.00%   56.04%   +0.03%     
==========================================
  Files         108      108              
  Lines       10049    10074      +25     
==========================================
+ Hits         5628     5646      +18     
- Misses       4140     4144       +4     
- Partials      281      284       +3     

Impacted Files	Coverage Δ
app/ante/ante.go	58.13% <73.33%> (+5.68%)	⬆️

[facs95]

Awesome work @GAtom22 👏