v1.18: chore: add CODEOWNERS (backport of #957) (#1021)

chore: add CODEOWNERS (#957)

(cherry picked from commit 748db1044862f2db8b36afc3253fe652d81fa315)

Co-authored-by: Yihau Chen <a122092487@gmail.com>

.github/CODEOWNERS

@@ -0,0 +1 @@
+* @anza-xyz/backport-reviewers @anza-xyz/releng