Upgrade markdown templates to issue forms (#2588)

.github/ISSUE_TEMPLATE/feature-request.yml

@@ -0,0 +1,34 @@
+name: 🌟 Feature request
+description: Suggest an enhancement for Sanic
+labels: ["feature request"]
+body:
+  - type: checkboxes
+    id: existing
+    attributes:
+      label: Is there an existing issue for this?
+      description: Please search to see if an issue already exists for the enhancement you are proposing.
+      options:
+      - label: I have searched the existing issues
+        required: true
+  - type: textarea
+    id: description
+    attributes:
+      label: Is your feature request related to a problem? Please describe.
+      description: A clear and concise description of what the problem is. Ex. I'm always frustrated when [...]
+    validations:
+      required: false
+  - type: textarea
+    id: code
+    attributes:
+      label: Describe the solution you'd like
+      description: A clear and concise description of what you want to happen.
+    validations:
+      required: true
+  - type: textarea
+    id: additional
+    attributes:
+      label: Additional context
+      description: Add any other context about the problem here.
+    validations:
+      required: false
+