Add pre-push git hook to prevent pushing to yugabyte repo

Summary:
1) Add hooks/ directory
2) Add pre-push python script

Test Plan:
```
ln -s hooks/pre-push .git/hooks/pre-push
ybd --sj
touch fakefile
git commit -am "test"
```
Attempt to push to yugabyte/{branch} and it should fail
Attempt to push to {other-repo}/{branch} and it should succeed

To test that this does not block `arc land`, we will see if landing this diff is successful..

Jenkins: skip

Reviewers: mikhail, jason

Reviewed By: mikhail, jason

Subscribers: devops

Differential Revision: https://phabricator.dev.yugabyte.com/D8957

hooks/pre-push

@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+
+import sys
+
+def run_pre_push_hook(remote_loc, remote_ref):
+    has_github = "github.com" in remote_loc.lower()
+    has_yb_repo = "yugabyte/yugabyte-db" in remote_loc.lower()
+    is_master_push = remote_ref == "refs/heads/master"
+
+    if has_github and has_yb_repo and not is_master_push:
+        sys.stderr.write(
+            "Cannot push any branch except master to yugabyte/yugabyte-db repo, "
+            "which should only be done when running arc land.")
+        return 1
+    return 0
+
+if __name__ == "__main__":
+    [remote_name, remote_loc] = sys.argv[1], sys.argv[2]
+    [local_ref, local_sha1, remote_ref, remote_sha1] = sys.stdin.read().split()
+    sys.exit(run_pre_push_hook(remote_loc, remote_ref))