Remove generated protobuf file from version control

Remove examples/tcp_rerouting/src/generated/ from git tracking and
add to .gitignore. Generated code should not be committed as it:
- Can be regenerated from the .proto file via build.rs
- Creates unnecessary diff noise when dependencies update
- Can get out of sync with source

The file is automatically generated during build by prost-build,
so this does not affect functionality.

Signed-off-by: Christof Gerber <christof.gerber1@gmail.com>

Author: SiiiTschiii

.gitignore

@@ -1,3 +1,5 @@
 /bazel-*
 target
 Cargo.lock
+# Generated protobuf code
+examples/tcp_rerouting/src/generated/