Add Bomr metadata for bom upgrades and verification

Closes gh-16060

.bomr/bomr.yaml

+bomr:
+  bom: spring-boot-dependencies/pom.xml
+  upgrade:
+    github:
+      organization: spring-projects
+      repository: spring-boot
+      issue-labels:
+        - 'type: dependency-upgrade'
+    policy: same-minor-version
+  verify:
+    repositories:
+      # Spring Data GemFire's GemFire dependencies
+      - https://repo.spring.io/gemstone-release-pivotal-cache