chore: update to alpine 3.20

[strophy]

Hi @rvolosatovs finally got around to making the changes needed to support Alpine 3.20. Main changes are:

• protoc_gen_scala build no longer works on arm64 (I might have a solution for this soon)
• protoc_gen_ts build is no longer possible due to the end of the pkg project in favour of Node Single Executable Applications. Since this is just the node binary with an additional payload, it is much easier to just include node in the final image and use NPM to install the plugin without complicated build/compile steps.
• grpc_web build process changed due to Alpine no longer shipping libraries for static linking, so now we need to build protobuf itself first to static link against.
• re-enable grpc_swift on arm64

[rvolosatovs]

Thanks! Looks like CI is failing though, could you take a look?

[strophy]

@rvolosatovs I ended up creating an Alpine package for Bazel 7, now that I can use that here, the build works! Any more comments or let's merge, then I can tidy up the remaining PRs after this big change is in.

[rvolosatovs]

Nice work!