chore(examples): Remove framework-specific examples

[donmccurdy]

Removes framework-specific examples from the repository. The dependencies (and necessary dependency updates) required to include three frameworks here are too much. We have framework-specific examples elsewhere in:

• https://github.com/CartoDB/carto-app-templates
• https://github.com/CartoDB/deck.gl-examples/

[jmgaya]

Amazing job and clean-up 💪

I absolutely agree that repeating templates between repositories feels wrong, as they may get outdated easily, but instead, keeping them all together elsewhere feels much more natural and easier to maintain 😄

[padawannn]

I agree with the changes but I would like to validate with @srtena first

[srtena]

Yes, no problem. I also think they aren't necessary and we should focus on the app-templates. Thanks team :)

Requested review was done.