Add preupload hooks config for NetworkStack

Adds Java and Kotlin linters in preupload.

Test: modified Java/Kotlin, tried upload, saw errors
Change-Id: I802209075df174768b8b692d241643808ec286e6
diff --git a/PREUPLOAD.cfg b/PREUPLOAD.cfg
new file mode 100644
index 0000000..151be7e
--- /dev/null
+++ b/PREUPLOAD.cfg
@@ -0,0 +1,3 @@
+[Hook Scripts]
+checkstyle_hook = ${REPO_ROOT}/prebuilts/checkstyle/checkstyle.py --sha ${PREUPLOAD_COMMIT}
+ktlint_hook = ${REPO_ROOT}/prebuilts/ktlint/ktlint.py -f ${PREUPLOAD_FILES}