Follow up work after devtools mvp

[chacha912]

What this PR does / why we need it?

• Import devtools types from yorkie-js-sdk and remove protocol.ts
• Center-align the panel
• Update README.md
• Change the Yorkie icon from 🐶 to 🐾
• Fix the issue where the panel doesn't update on page refresh
• Deploy using GitHub Actions (next PR)
• Add design documentation for devtools event and lifecycle (next PR)

Any background context you want to provide?

What are the relevant tickets?

Fixes #

Checklist

• Added relevant tests or not required
• Didn't break anything

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (3b0cca9) 81.11% compared to head (de7c38d) 81.09%.

Files	Patch %	Lines
src/devtools/index.ts	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #734      +/-   ##
==========================================
- Coverage   81.11%   81.09%   -0.03%     
==========================================
  Files          59       59              
  Lines        4289     4289              
  Branches      838      838              
==========================================
- Hits         3479     3478       -1     
+ Misses        550      549       -1     
- Partials      260      262       +2     

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[hackerwins]

Thanks for your contribution. 👍