Replaced old markdown Issue template with new GitHub forms templates (#3468)

This PR replaces the old markdown issue template with the new YAML based form templates for GitHub, this allows us to enforce required fields and also auto-tag with labels.

This doesn't remove the ability to open a blank issue, but it is obscured so it is not the primary thing people are likely to do.

This also added link entries in the issue creation page to link to the Discussions tab, Community Slack, and IRC channel.

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,26 @@
+name: Feature Request
+description: "Submit a feature request for Yosys" 
+labels: ["feature-request"]
+body:
+  - type: markdown
+    attributes:
+      value: >
+
+        If you have a general question, please ask it in the [Discussions](https://github.com/YosysHQ/yosys/discussions) area
+        or join our [IRC Channel](https://web.libera.chat/#yosys) or [Community Slack](https://join.slack.com/t/yosyshq/shared_invite/zt-1aopkns2q-EiQ97BeQDt_pwvE41sGSuA).
+        
+
+        If you have a bug report, please fill out the appropriate issue form, this form is for feature requests.
+
+        
+        Please contact [YosysHQ GmbH](https://www.yosyshq.com/) if you need
+        commercial support or work done for Yosys.
+
+  - type: textarea
+    id: feature_description
+    attributes:
+      label: Feature Description
+      description: "A clear and detailed description of the feature."
+    validations:
+      required: true
+