Support Abseil/RE2 in Bazel + Docker

[martijneken]

Opening a tracking issue to communicate where I am with this:

• Support for full Abseil/RE2 is working with Bazel: Full Abseil + RE2 support #173
• I ran into issues with the make/Docker SDK, so I am reworking some things:
  • Use cmake builds (requires Protobuf update, I'm targeting v26.1)
  • Get rid of static protobuf libs
  • Use a single wasm makefile for all configs
  • Update / simplify the docs: https://github.com/proxy-wasm/proxy-wasm-cpp-sdk/blob/main/docs/building.md

[martijneken]

Reopening for a patch that makes absl::random work