meta: add required fields in issue templates

Make sure there is at least one required field in each issue template.
Leave the title blank to enforce that as a required field as well.

PR-URL: https://github.com/nodejs/node/pull/41378
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

.github/ISSUE_TEMPLATE/1-bug-report.yml

@@ -39,6 +39,8 @@ body:
     attributes:
       label: What do you see instead?
       description: If possible please provide textual output instead of screenshots.
+    validations:
+      required: true
   - type: textarea
     attributes:
       label: Additional information

.github/ISSUE_TEMPLATE/2-feature-request.yml

@@ -11,9 +11,13 @@ body:
   - type: textarea
     attributes:
       label: What is the problem this feature will solve?
+    validations:
+      required: true
   - type: textarea
     attributes:
       label: What is the feature you are proposing to solve the problem?
+    validations:
+      required: true
   - type: textarea
     attributes:
       label: What alternatives have you considered?

.github/ISSUE_TEMPLATE/3-api-ref-docs-problem.yml

@@ -1,7 +1,6 @@
 name: "\U0001F4D7 Open an issue regarding the Node.js API reference docs"
 description: Let us know about any problematic API reference documents
 labels: ["doc"]
-title: 'doc: <title>'
 body:
   - type: markdown
     attributes:
@@ -14,4 +13,6 @@ body:
       label: Affected URL(s)
   - type: textarea
     attributes:
-      label: Explanation of the problem
+      label: Description of the problem
+    validations:
+      required: true

.github/ISSUE_TEMPLATE/4-report-a-flaky-test.yml

@@ -1,6 +1,5 @@
 name: Report a flaky test
 description: Report a flaky test in our CI
-title: "Investigate flaky test - "
 labels: ["flaky-test"]
 body:
   - type: markdown