NH-119445: add dependabot.yaml and pull_request_template.md

.github/dependabot.yaml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: "maven"
+    directory: "/"
+    schedule:
+      interval: "weekly"

.github/pull_request_template.md

@@ -0,0 +1,9 @@
+**Tl;dr**: [optional] 1-liner if the context of the change is long
+
+**Context**:
+
+Few sentences on the changes. Maybe link to relevant design docs or discussion if any.
+
+**Test Plan**:
+
+How it was tested or going to be tested