Heron Protocol Buffers Migration to Native Bazel Rules

We need to generate the Python protobuf and use Bazel's native rules for Java and CC. Java and CC examples are here.

Working on assembling the Protobuf in isolation on this repository for PR #3768.

Automated BUILD file generation using Gazelle

Protocol Buffer BUILD files are located in the proto/ directory.

To generate/update the BUILD files run bazel run //:gazelle -- proto from the repository root directory.

Directory Tree

├── proto
│   ├── api
│   │   ├── BUILD.bazel
│   │   └── topology.proto
│   ├── ckptmgr
│   │   ├── BUILD.bazel
│   │   └── ckptmgr.proto
│   ├── scheduler
│   │   ├── BUILD.bazel
│   │   └── scheduler.proto
│   ├── stmgr
│   │   ├── BUILD.bazel
│   │   └── stmgr.proto
│   ├── system
│   │   ├── BUILD.bazel
│   │   ├── common.proto
│   │   ├── execution_state.proto
│   │   ├── metrics.proto
│   │   ├── packing_plan.proto
│   │   ├── physical_plan.proto
│   │   ├── stats.proto
│   │   └── tuple.proto
│   ├── testing
│   │   ├── BUILD.bazel
│   │   └── networktests.proto
│   └── tmanager
│       ├── BUILD.bazel
│       └── tmanager.proto