chore: move wasm binary to cmd/wasm

[thomaspoignant]

Description

Move wasm directory to cmd/wasm because this is a binary in the end.
All binaries build should be available in the cmd directory.

Checklist

• I have tested this code
• I have followed the contributing guide

[netlify]

✅ Deploy Preview for go-feature-flag-doc-preview canceled.

Name	Link
🔨 Latest commit	d9f8661
🔍 Latest deploy log	https://app.netlify.com/projects/go-feature-flag-doc-preview/deploys/68ef4e63e09f8300089c634b

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.76%. Comparing base (e4661ca) to head (d9f8661).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #4099   +/-   ##
=======================================
  Coverage   83.76%   83.76%           
=======================================
  Files         139      139           
  Lines        6831     6831           
=======================================
  Hits         5722     5722           
+ Misses        899      898    -1     
- Partials      210      211    +1     

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