feat: object-syntax event handlers

[danielroe]

🔗 Linked issue

#417
resolves #424

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This supports object-syntax event handlers with the following syntax:

defineEventHandler({
  handler: () => {},
  before: [],
  after: []
})

Helper validate functions need to be drafted that type-hint event and infer a return type. (I would suggest we also suggest validate: { body: () => {}, query: () => {} } which I think will be easier to directly get a type from as user can just return the validated body/query, which we can then flow through into rest of handlers.)

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[codecov]

Codecov Report

Merging #485 (36da183) into main (7fc1d8b) will decrease coverage by 0.45%.
Report is 2 commits behind head on main.
The diff coverage is 58.18%.

❗ Current head 36da183 differs from pull request most recent head 7e192af. Consider uploading reports for the commit 7e192af to get more accurate results

@@            Coverage Diff             @@
##             main     #485      +/-   ##
==========================================
- Coverage   82.79%   82.34%   -0.45%     
==========================================
  Files          31       31              
  Lines        3424     3473      +49     
  Branches      514      516       +2     
==========================================
+ Hits         2835     2860      +25     
- Misses        589      613      +24     

Files Changed	Coverage Δ
src/event/utils.ts	62.67% <45.23%> (-9.71%)	⬇️
src/types.ts	100.00% <100.00%> (ø)
src/utils/cookie.ts	93.78% <100.00%> (ø)