Add Makefile to generate python files based on idl definition

[timl3136]

Summary

Adds a Makefile that automates generation of Python protobuf files from Cadence's IDL definitions. Processes both API and Admin protobuf files from idls/proto/uber/cadence/ and generates corresponding Python _pb2.py files in .gen/ directory.

Changes

• Makefile - Build automation with targets: all (default), clean, help, show
• 20 generated Python files in .gen/uber/cadence/api/v1/ and .gen/uber/cadence/admin/v1/

Usage

make        # Generate all Python proto files
make clean  # Remove generated files
make help   # Show available targets

Prerequisites

• protoc (Protocol Buffers compiler) in PATH
• Source .proto files in idls/proto/uber/cadence/

[Groxx]

we probably want to copy the protoc download-and-init-in-temp-build-dir thing from the other cadence repos :\ protoc's code is far from stable across versions.

[timl3136]

protoc v3.14.0 does not have pyi support, should I just a separate version for the pyi files? I think .pyi files are quite essential for dev to understand type definition.

[Groxx]

there's no need for it to be the same version as go/java, we can just pick a newer one. they're all wire-binary-compatible with each other, and we have no code-API backwards compatibility needs that would force us on an older version (unlike go/java)

[Groxx]

possible alternative to these, for makefile-debugging purposes:

$(info $(API_PROTO_FILES))

^ basically anywhere, but generally at parse-time (outside any target).

(tbh I think these "help understand the makefile" targets are completely fine while things are simple, so this LGTM as-is. just offering an alternative for future debug-sessions. remake is also truly excellent and highly recommended)

[Groxx]

copying from side-chat:

• yea seems reasonable, happy to approve if it'll streamline anything.
• versioned-protoc seems probably critical eventually. it's a really big pain as time passes.
• .pyi files seem like a good idea to include
• it's currently written with every file doing a separate protoc run. in other languages that tends to cause problems if you make protoc -j to run them in parallel, because it has a nasty habit of clobbering other files / reading partially-written files and getting confused.
  • is that an issue in python? if no, the setup now is ideal. if yes, we should probably pull it into a single protoc-target that runs them all in a specific way.

---

make -j seems fine, so 👍 that's a nice way to do it.

also we might want to pull in the submodule-check from the server repo, since this silently does nothing if the submodule isn't initialized.
(also entirely fine as-is for now, just future polish stuff)

[shijiesheng]

Python uses pyproject. Please refer to https://github.com/temporalio/sdk-python/blob/main/pyproject.toml on how to add build-system.