refactor(crypto): use elliptic/lib/elliptic/ec/signature

[ghost]

Description

This PR fixes #385.

Motivation and Context

How has this been tested?

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• Add tests to cover changes as needed.
• Update documentation as needed.

[codecov-commenter]

Codecov Report

Merging #386 (ccc8bd4) into dev (5812a8d) will decrease coverage by 0.06%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##              dev     #386      +/-   ##
==========================================
- Coverage   80.98%   80.92%   -0.07%     
==========================================
  Files          44       43       -1     
  Lines        1804     1798       -6     
  Branches      329      327       -2     
==========================================
- Hits         1461     1455       -6     
  Misses        342      342              
  Partials        1        1              

Impacted Files	Coverage Δ
packages/zilliqa-js-crypto/src/index.ts	100.00% <100.00%> (ø)
packages/zilliqa-js-crypto/src/schnorr.ts	87.20% <100.00%> (ø)

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