Refactor `nanopb.bzl` and encapsulate similar functionality

[Andrewyx]

Description of the task

nanopb.bzl implements the nanopb_proto_library rule and is extremely complicated. It uses protoc and the nanopb plugin to generate nanopb proto libs, a zip containing our nanopb.c and nanopb.h for ESPs, and C++ artifacts for cc_library targets.

Specifically, this rule outputs the following 3 bazel types:

1. DefaultInfo : For flashing onto ESPs
2. CcInfo: C++ output artifacts
3. PlatformIOLibraryInfo: For platformio_rules

We should separate the internal logic for performing these three actions, so that this already difficult to read code is more maintainable.

Acceptance criteria

• nanopb.bzl should be SOLID

Blocked By

• Andrewyx/Upgrade Bazel 8 #3459