Remove examples extra in favor of individual example deps

[btjanaka]

Description

It seems troublesome to have to install dependencies for all examples with ribs[examples] when you only want to run a single example. Thus, this PR switches the dependencies to be associated with each script, much like the tutorials.

TODO

Questions

Status

• [x] I have read the guidelines in CONTRIBUTING.md
• [x] I have formatted my code using yapf
• [x] I have tested my code by running pytest
• [x] I have linted my code with pylint
• [x] I have added a one-line description of my change to the changelog in HISTORY.md
• [x] This PR is ready to go