Added codeowners

Author: aravindbuilt

.github/CODEOWNERS

@@ -0,0 +1,6 @@
+* @contentstack/devex-pr-reviewers
+.github/workflows/sca-scan.yml @contentstack/security-admin
+.github/workflows/issues-jira.yml @contentstack/security-admin
+.github/workflows/policy-scan.yml @contentstack/security-admin
+.github/workflows/secrets-scan.yml @contentstack/security-admin
+**/.snyk @contentstack/security-admin