Improve issue templates & add PR template (#7051)

* improved feature suggestion template

* added test case chapter to bug report template

* PR wording

* added PR template

* improved formatting in issue template

* removed checkbox for concept due to new GH discussions process

* improved wording

* improved PR todo list

* amended PR checklist; minor rewording

* removed duplicate wording

* add securtiy check section to contribution guide

.github/PULL_REQUEST_TEMPLATE/pull_request_template.md

@@ -0,0 +1,30 @@
+### New Pull Request Checklist
+<!--
+    Please check the following boxes [x] before submitting your issue.
+    Click the "Preview" tab for better readability.
+    Thanks for contributing to Parse Server!
+-->
+
+- [ ] I am not disclosing a [vulnerability](https://github.com/parse-community/parse-server/blob/master/SECURITY.md).
+- [ ] I am creating this PR in reference to an [issue](https://github.com/parse-community/parse-server/issues?q=is%3Aissue).
+
+### Issue Description
+<!-- Add a brief description of the issue this PR solves. -->
+
+Related issue: FILL_THIS_OUT
+
+### Approach
+<!-- Add a description of the approach in this PR. -->
+
+### TODOs before merging
+<!--
+    Add TODOs that need to be completed before merging this PR.
+    Delete suggested TODOs that do not apply to this PR.
+-->
+
+- [ ] Add test cases
+- [ ] Add entry to changelog
+- [ ] Add changes to documentation (guides, repository pages, in-code descriptions)
+- [ ] Add [security check](https://github.com/parse-community/parse-server/blob/master/CONTRIBUTING.md#security-checks)
+- [ ] Add new Parse Error codes to Parse JS SDK <!-- no hard-coded error codes in Parse Server -->
+- [ ] ...