Fix some of TS typing issues

[azygis]

Description

Types for features property is wrong on vector source amongst some other places. This PR is making them right.

Motivation and Context

Fixes #399.

How Has This Been Tested?

vitest and playwright tests have been run. Typings should not impact the functionality itself though.

Types of Changes

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation Update
• Tests
• Other (Tooling, Dependency Updates, etc.) - TS typings

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I added a new test.

[netlify]

✅ Deploy Preview for vue3openlayers ready!

Name	Link
🔨 Latest commit	a0b06a1
🔍 Latest deploy log	https://app.netlify.com/sites/vue3openlayers/deploys/6762b8864ca861000724401b
😎 Deploy Preview	https://deploy-preview-400--vue3openlayers.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.