refactor: use pre-built protoc binary

Saves a bunch of time in analysis and execution when there is a cache miss on protoc,
as well as avoiding a bunch of gcc logspam.

Author: alexeagle

.bazelrc

@@ -1 +1,6 @@
 run --workspace_status_command="bash tools/workspace-status.sh"
+
+# Don't build protoc from the cc_binary, it's slow and spammy when cache miss
+common --per_file_copt=external/.*protobuf.*@--PROTOBUF_WAS_NOT_SUPPOSED_TO_BE_BUILT
+common --host_per_file_copt=external/.*protobuf.*@--PROTOBUF_WAS_NOT_SUPPOSED_TO_BE_BUILT
+common --incompatible_enable_proto_toolchain_resolution

MODULE.bazel

@@ -14,6 +14,7 @@ bazel_dep(name = "rules_oci", version = "2.2.5")
 bazel_dep(name = "rules_pkg", version = "1.0.1")
 bazel_dep(name = "rules_proto", version = "7.1.0")
 bazel_dep(name = "toolchains_llvm", version = "1.3.0")
+bazel_dep(name = "toolchains_protoc", version = "0.4.2")
 
 git_override(
     module_name = "bazel_remote_apis",
@@ -31,6 +32,14 @@ single_version_override(
     patches = ["//:patches/jsonnet/bazel-8.diff"],
 )
 
+protoc = use_extension("@toolchains_protoc//protoc:extensions.bzl", "protoc")
+
+# Match protobuf above, until it ships a pre-built binary toolchain itself
+protoc.toolchain(version = "v29.3")
+use_repo(protoc, "toolchains_protoc_hub")
+
+register_toolchains("@toolchains_protoc_hub//:all")
+
 go_sdk = use_extension("@rules_go//go:extensions.bzl", "go_sdk")
 go_sdk.download(version = "1.24.0")