chore: update feature request template by using Github issue forms. (#15158)

.github/ISSUE_TEMPLATE/feature_request.md

@@ -1,27 +0,0 @@
----
-name: Feature request
-about: Request an enhancement for Nvim
-title: ''
-labels: enhancement
-
----
-
-<!-- Before reporting: search existing issues and check the FAQ. -->
-
-- `nvim --version`:
-- `vim -u DEFAULTS` (version: ) behaves differently?
-- Operating system/version:
-- Terminal name/version:
-- `$TERM`:
-
-### Steps to reproduce using `nvim -u NORC`
-
-```
-nvim -u NORC
-
-```
-
-### Actual behaviour
-
-### Expected behaviour
-

.github/ISSUE_TEMPLATE/feature_request.yml

@@ -0,0 +1,20 @@
+name: Feature request
+description: Request an enhancement for Neovim
+labels: [enhancement]
+body:
+
+  - type: markdown
+    attributes:
+      value: |
+        Before requesting: search [existing issues](https://github.com/neovim/neovim/labels/enhancement) and check the [FAQ](https://github.com/neovim/neovim/wiki/FAQ).
+
+  - type: input
+    attributes:
+      label: "Feature already in Vim?"
+      description: "Does the feature already exist in Vim? If possible, please specify which version of Vim it was introduced in."
+
+  - type: textarea
+    attributes:
+      label: "Feature description"
+    validations:
+      required: true