Added github "issue templates" for bug reports and new feature requests

[ysuarez]

What this PR does / why we need it:
Adds github "issue templates" for bug reports and new feature requests. It is a way to be welcoming to new contributors that are not used to submitting Github bug requests or feature requests.

This commit also removed a file called "ISSUE_TEMPLATE.md" that used an older style of Github templates, and removed a bit of some now unneeded content from CONTRIBUTING.md.

Which issue(s) this PR closes:

Closes #6227

Though this PR may need changes before it can close this issue.

Special notes for your reviewer:

Suggestions on how to test this:

Please review wording and grammar used.

Not 100% how to test before merging this commit, since this is a Github specific behavior. Therefore it may require the commit(s) to be added to the DV main repo in the repo's "default branch" before the GIthub site picks up these templates when creating a new issues.

Does this PR introduce a user interface change? If mockups are available, please link/include them here:
No

Is there a release notes update needed for this change?:
No

Additional documentation:

Note: For additional consideration based on this branch

Github issue templates allow for...

1. Placeholder "titles" of issues. As an experiment I made the placeholder title of the feature request be "Feature Request/Idea:", but it could be left blank.

2. Pre-labeling of issues. That means that, for example, you could create a new label like "Features: uncategorized" for new features to better track them.

3. Pre-assigning repo users to new issues. If you wanted a certain users to be assigned to new bugs or features.

4. A config.yml file can be used to further tweak the template chooser, but I will wait for the first commit to be merged before trying to experiment with config.yml. More info here: [Configuring the template chooser](https://docs.github.com/en/communities/using-templates-to-encourage-useful-issues-and-pull-requests/configuring-issue-templates-for-your-repository#configuring-the-template-chooser0

[djbrooke]

Hey @ysuarez - thanks for this! We'll take a look!

[djbrooke]

Hey @ysuarez thank you and sorry for the delay in getting to this. I've added some feedback and suggestions. I think pointing people to existing issues is definitely a best practice but I think we should plan to revisit in the future once our issue tracker is in better shape (this is one of my short term goals). Thanks again and let me know if you have any questions!

[ysuarez]

@djbrooke thanks for the feedback. I think I put in all your recommendations, but let me know if I miss any. I still think we cannot see these in action until we merge the changes in. At that point the community may have changes to suggest.

[djbrooke]

Thanks @ysuarez! I agree, this is one where we can roll it out and see what works for the community or if they have suggestions. I'll move this to QA. Thank you again for the PR!