Implement Local Remote Execution for Rust

This change implements ~40 Rust toolchains that reuse Nix's executables
and make them available via Bazel.

The new setup is fully reproducible, supports musl and glibc and
works from all nix-supported hosts to all sensible crosscompilation
targets seamlessly through remote and local execution.

For instance, you can now run this command on a MacOS host to build a
statically linked executable for x86_64-linux on a remote arm worker:

```bash
bazel build \
    nativelink \
    --extra_execution_platforms=@local-remote-execution//lre-rs:aarch64-unknown-linux-gnu \
    --platforms=@local-remote-execution//lre-rs:x86_64-unknown-linux-musl
```

.bazelignore

@@ -13,3 +13,4 @@ bazel-testlogs
 bazel-nativelink
 local-remote-execution/generated-cc
 local-remote-execution/generated-java
+local-remote-execution/lre-rs

MODULE.bazel

@@ -6,7 +6,7 @@ module(
 
 bazel_dep(name = "rules_cc", version = "0.0.17")
 bazel_dep(name = "platforms", version = "0.0.10")
-bazel_dep(name = "rules_python", version = "0.36.0")
+bazel_dep(name = "rules_python", version = "0.40.0")
 
 python = use_extension("@rules_python//python/extensions:python.bzl", "python")
 python.toolchain(
@@ -20,6 +20,12 @@ use_repo(python, python = "python_versions")
 
 bazel_dep(name = "rules_rust", version = "0.54.1")
 
+# TODO(aaronmondal): REMOVE
+local_path_override(
+    module_name = "rules_rust",
+    path = "../rules_rust",
+)
+
 rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
 rust.toolchain(
     edition = "2021",
@@ -40,19 +46,19 @@ rust.toolchain(
         "2024-11-23/rustfmt-nightly-x86_64-unknown-linux-gnu.tar.xz": "ac2a8fff891473220d36c9e62afc2dc0d5aebaefbb8489584bd2446a37d6fd7b",
     },
     versions = [
-        "1.82.0",
-        "nightly/2024-11-23",
+        # "1.82.0",
+        # "nightly/2024-11-23",
     ],
 )
 
-rust_host_tools = use_extension(
-    "@rules_rust//rust:extension.bzl",
-    "rust_host_tools",
-)
-rust_host_tools.host_tools(
-    edition = "2021",
-    version = "1.82.0",
-)
+# rust_host_tools = use_extension(
+#     "@rules_rust//rust:extension.bzl",
+#     "rust_host_tools",
+# )
+# rust_host_tools.host_tools(
+#     edition = "2021",
+#     version = "1.82.0",
+# )
 
 use_repo(rust, "rust_toolchains")
 
@@ -64,23 +70,25 @@ crate.from_cargo(
     supported_platform_triples = [
         "aarch64-apple-darwin",
         "aarch64-unknown-linux-gnu",
+        "aarch64-unknown-linux-musl",
         "arm-unknown-linux-gnueabi",
         "armv7-unknown-linux-gnueabi",
         "x86_64-apple-darwin",
         "x86_64-pc-windows-msvc",
         "x86_64-unknown-linux-gnu",
+        "x86_64-unknown-linux-musl",
     ],
 )
 use_repo(crate, "crates")
 
-rust_analyzer = use_extension(
-    "@rules_rust//tools/rust_analyzer:extension.bzl",
-    "rust_analyzer_dependencies",
-)
-rust_analyzer.rust_analyzer_dependencies()
+# rust_analyzer = use_extension(
+#     "@rules_rust//tools/rust_analyzer:extension.bzl",
+#     "rust_analyzer_dependencies",
+# )
+# rust_analyzer.rust_analyzer_dependencies()
 
-bazel_dep(name = "protobuf", version = "27.5", repo_name = "com_google_protobuf")
-bazel_dep(name = "toolchains_protoc", version = "0.3.3")
+bazel_dep(name = "protobuf", version = "29.0", repo_name = "com_google_protobuf")
+bazel_dep(name = "toolchains_protoc", version = "0.3.4")
 
 protoc = use_extension("@toolchains_protoc//protoc:extensions.bzl", "protoc")
 protoc.toolchain(