crypto/ecpointgrouplaw: support Ed25519

[cychuang0924]

Before submitting a pull request, please make sure the following is done:

Checklist

• Fork the repository and create your new branch from master.
• Please mention the name of community in Pull Request title.
• Git Commit Messages
  • Use the present tense (Also in Pull Request title): "Add feature" not "Added feature"
  • Use the imperative mood (Also in Pull Request title): "Move cursor to..." not "Moves cursor to..."
  • Use rebase to squash/fixup dummy/unnecessary commits into only one commit.

[codecov]

Codecov Report

Merging #137 (4831138) into master (e1dab0a) will increase coverage by 0.01%.
The diff coverage is 100.00%.

❗ Current head 4831138 differs from pull request most recent head 1ce4668. Consider uploading reports for the commit 1ce4668 to get more accurate results

@@            Coverage Diff             @@
##           master     #137      +/-   ##
==========================================
+ Coverage   84.66%   84.67%   +0.01%     
==========================================
  Files          91       91              
  Lines        6644     6649       +5     
==========================================
+ Hits         5625     5630       +5     
  Misses        605      605              
  Partials      414      414              

Impacted Files	Coverage Δ
crypto/ecpointgrouplaw/point.go	98.62% <100.00%> (+0.04%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update bb68f25...1ce4668. Read the comment docs.