User warnings large upload

[hh-space-invader]

Add user warnings if uploading or loading collection with more than 20K points in local mode.
I've refactored the way we do DeprecationWarning as we also want to add UserWarning to be shown once by adding show_warning and show_warning_once and then specify the category of the warning needed to be shown once.

All Submissions:

• Contributions should target the dev branch. Did you create your branch from dev?
• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

New Feature Submissions:

1. Does your submission pass tests?
2. Have you installed pre-commit with pip3 install pre-commit and set up hooks with pre-commit install?

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you successfully ran tests with your changes locally?

[netlify]

✅ Deploy Preview for poetic-froyo-8baba7 ready!

Name	Link
🔨 Latest commit	2bded2f
🔍 Latest deploy log	https://app.netlify.com/sites/poetic-froyo-8baba7/deploys/67519426e888480008269077
😎 Deploy Preview	https://deploy-preview-852--poetic-froyo-8baba7.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.