refactor: notification component

[mlmoravek]

This is part of #606

In this PR I refactored the notification component from Options-API to Composition-API.

Proposed Changes

• Updated Notification to composition api
• Updated Notification programmatic usage
• Remove unused mixin
• Docs: add sub componenten description

[netlify]

✅ Deploy Preview for oruga-documentation-preview ready!

Name	Link
🔨 Latest commit	4aae4fd
🔍 Latest deploy log	https://app.netlify.com/sites/oruga-documentation-preview/deploys/6522fc7b913f2100088027b9
😎 Deploy Preview	https://deploy-preview-620--oruga-documentation-preview.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[codecov]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (b056187) 63.86% compared to head (4aae4fd) 63.84%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #620      +/-   ##
===========================================
- Coverage    63.86%   63.84%   -0.02%     
===========================================
  Files           87       87              
  Lines         5606     5606              
  Branches      1587     1587              
===========================================
- Hits          3580     3579       -1     
- Misses        1915     1916       +1     
  Partials       111      111              

Flag	Coverage Δ
oruga	65.92% <ø> (ø)
oruga-next	55.10% <ø> (-0.10%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

see 1 file with indirect coverage changes

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.