Add toolchain parameter to the affected actions (#2140)

This is part of the migration of Automatic Exec Groups ([AEGs design
doc](https://docs.google.com/document/d/1-rbP_hmKs9D639YWw5F_JyxPxL2bi6dSmmvj_WXak9M/edit#heading=h.5mcn15i0e1ch)).

In this PR I've added a `toolchain` param to the affected actions
(actions for which we can't detect if their tools/executable are coming
from a toolchain). That's why sometimes it's set to None. The
`toolchain` param is visible from Bazel 6.0, which rules_rust already
supports.

**Important note to reviewers**: Please check if the correct toolchain
type is added for each action. I’ve done my best, but additional
precaution is not harmful. 🙂

Also note that this toolchain param is not used right now since AEGs are
still not enabled (there should be no errors). This is mostly step
forward for the internal changes, and I will focus on enabling AEGs in
Bazel after it's fully tested inside Google.

cargo/private/cargo_build_script.bzl

@@ -256,6 +256,7 @@ def _cargo_build_script_impl(ctx):
         mnemonic = "CargoBuildScriptRun",
         progress_message = "Running Cargo build script {}".format(pkg_name),
         env = env,
+        toolchain = None,
     )
 
     return [

rust/private/clippy.bzl

@@ -178,6 +178,7 @@ See https://github.com/bazelbuild/rules_rust/pull/1264#discussion_r853241339 for
         tools = [toolchain.clippy_driver],
         arguments = args.all,
         mnemonic = "Clippy",
+        toolchain = "@rules_rust//rust:toolchain_type",
     )
 
     return [

rust/private/rustc.bzl

@@ -1268,6 +1268,7 @@ def rustc_compile_action(
                 formatted_version,
                 len(crate_info.srcs.to_list()),
             ),
+            toolchain = "@rules_rust//rust:toolchain_type",
         )
         if args_metadata:
             ctx.actions.run(
@@ -1283,6 +1284,7 @@ def rustc_compile_action(
                     formatted_version,
                     len(crate_info.srcs.to_list()),
                 ),
+                toolchain = "@rules_rust//rust:toolchain_type",
             )
     else:
         # Run without process_wrapper
@@ -1301,6 +1303,7 @@ def rustc_compile_action(
                 formatted_version,
                 len(crate_info.srcs.to_list()),
             ),
+            toolchain = "@rules_rust//rust:toolchain_type",
         )
 
     if experimental_use_cc_common_link: