Create a template for opening issues

[sishida]

We need to create a template that contributors can fill out when they want to open a new issue in this Codewind repository.

Examples of existing templates:

• Microclimate: https://github.com/microclimate-dev2ops/microclimate-dev2ops.github.io/tree/master/.github/ISSUE_TEMPLATE
• Codewind VS Code: https://github.com/eclipse/codewind-vscode/blob/master/.github/ISSUE_TEMPLATE/bug_report.md
• Che: chore(github): Update issue template to have several choices eclipse-che/che#13777

Questions to consider:

• Do we want one template (like Microclimate) or multiple templates for different kinds of issues (like Che)?
• If committers are the only ones who can add labels to issues, what should be the process for notifying committers of newly created issues so that they can add the labels?