feat: VI-13156 Adds Python protoc.sh support

[VI-13156](https://outreach-io.atlassian.net/browse/VI-13156)

Adds support for building Python protobuf client stubs.  Adds pinned
versions for the relevant tools in `versions.yaml`.

This Python build script eschews fancier systems like `poetry` or `uv`
in favor of managing its own virtualenv.  It maintains a virtualenv
under a `.venv-codegen` directory under the repo's root and installs the
necessary tools (grpcio, betterproto) there.

Also adds some placeholders for Python package building and publishing.

Author: richardlarocque

shell/protoc.sh

@@ -293,3 +293,39 @@ if has_grpc_client "ruby"; then
     popd || exit 1
   fi
 fi
+
+if has_grpc_client "python"; then
+  info "Generating Python gRPC client"
+
+  # Create a dedicated virtualenv for codegen tools
+  VENV_DIR="$HOME/.outreach/.cache/$(get_app_name)/venv-codegen"
+  VENV_PYTHON="$VENV_DIR/bin/python"
+  VENV_PIP="$VENV_DIR/bin/pip"
+
+  if [ ! -d "$VENV_DIR" ]; then
+    info_sub "Creating virtualenv for code generation tools"
+    python -m venv "$VENV_DIR"
+  fi
+
+  info_sub "Ensuring Python protoc plugins are installed"
+
+  python_grpcio_tools_version="$(get_application_version "python-grpcio-tools")"
+  betterproto_version="$(get_application_version "betterproto")"
+
+  "$VENV_PIP" install --quiet \
+    "grpcio-tools==$python_grpcio_tools_version" \
+    "betterproto[compiler]==$betterproto_version"
+
+  # Make python output directory if it doesn't exist.
+  mkdir -p "$(get_repo_directory)$workDir/clients/python/src/$(get_app_name)_client/generated"
+
+  info_sub "Running Python protobuf generation"
+
+  python_args=("${default_args[@]}")
+  python_args+=(
+    --python_betterproto_out="$(get_repo_directory)$workDir/clients/python/src/$(get_app_name)_client/generated"
+    --proto_path "$(get_repo_directory)$workDir$SUBDIR"
+  )
+
+  "$VENV_PYTHON" -m grpc_tools.protoc "${python_args[@]}" "$(get_repo_directory)$workDir$SUBDIR/"*.proto
+fi

shell/python/build.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+# Builds a python package
+
+set -e
+
+echo "TODO(VI-13156): Python packaging not yet implemented"
+exit 0

shell/python/publish.sh

@@ -0,0 +1,7 @@
+#!/usr/bin/env bash
+# Publishes a python package
+
+set -e
+
+echo "TODO(VI-13156): Python package publishing not yet implemented"
+exit 0

versions.yaml

@@ -22,6 +22,8 @@ node-grpc-tools: 1.11.2
 # https://github.com/getoutreach/stencil-golang/blob/main/templates/api/clients/ruby/client.gemspec.tpl
 ruby-grpc-tools: 1.72.0
 node-ts-grpc-tools: 5.3.2
+python-grpcio-tools: 1.76.0
+betterproto: 2.0.0-beta7
 
 # latest Go protobuf modules
 protoc-gen-go-latest: 1.31.0