Update issue templates

This PR updates our issue templates to switch away from the legacy issue templates. The new version in GitHub allows users to chose if they want to report an issue or propose a feature. See the GitHub docs for screenshots: https://docs.github.com/en/github/building-a-strong-community/configuring-issue-templates-for-your-repository#configuring-the-template-chooser

Author: marvinhagemeister

.github/ISSUE_TEMPLATE.md

@@ -0,0 +1,25 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+- [ ] Check if updating to the latest Preact version resolve the issue
+
+**Describe the bug**
+A clear and concise description of what the bug is.
+
+**To Reproduce**
+
+If possible, please provide a CodeSandbox/Codepen that demonstrates the issue. You can use the following template: https://codesandbox.io/s/preact-x-preact-cli-3-starter-vj285y2rn3
+
+Steps to reproduce the behavior:
+1. Go to '...'
+2. Click on '....'
+3. See error
+
+**Expected behavior**
+What should have happened when following the steps above?

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,14 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: feature request
+assignees: ''
+
+---
+
+**Describe the feature you'd love to see**
+A clear and concise description of what you'd love to see added to Preact.
+
+**Additional context (optional)**
+Add any other context or screenshots about the feature request here.