Add feature request issue template

[davidgit]

Description of the changes

Add a detailed description and purpose of your changes. Link the issue it solves (if there is one).

PR Review Checklist

Author

• [ ] the PR should focus on a single subject. Change only relevant files to the problem you’re working on Clean and format the code
• [ ] add unit tests for your changes and make sure all unit tests are passing
• [ ] add a risk label after carefully considering the "blast radius" of your changes
• [ ] describe the intent of your changes in the description. don't just rewrite your code in prose
• [ ] assign at least one reviewer
• [ ] address the feedback
• [ ] add a "ready for review" label. Only PRs with this label will be reviewed.

Reviewer

• [ ] review code for readability
• [ ] verify that high risk behavior changes are well tested
• [ ] check license for any new external dependency
• [ ] ask questions about anything that isn't clear and obvious
• [ ] approve the PR when you consider it's good to merge