workspace: add Rust EFI infrastructure

This bumps rules_rust, cleans up the toolchains with the new version.
It also adds the Prost codegen to "normal" crate set as well as a new
crate set specific to EFI. This is separate because of Rust no-std's
dependence on create feature tags.

Change-Id: Ie76e66ee83696948391420ca3b011a3a71258690
Reviewed-on: https://review.monogon.dev/c/monogon/+/2202
Tested-by: Jenkins CI
Reviewed-by: Serge Bazanski <serge@monogon.tech>
diff --git a/third_party/rust_efi/cargo/remote/BUILD.bazel b/third_party/rust_efi/cargo/remote/BUILD.bazel
new file mode 100644
index 0000000..b49fb68
--- /dev/null
+++ b/third_party/rust_efi/cargo/remote/BUILD.bazel
@@ -0,0 +1,17 @@
+# Export file for Stardoc support
+exports_files(
+    glob([
+        "**/*.bazel",
+        "**/*.bzl",
+    ]),
+    visibility = ["//visibility:public"],
+)
+
+filegroup(
+    name = "srcs",
+    srcs = glob([
+        "**/*.bazel",
+        "**/*.bzl",
+    ]),
+    visibility = ["//visibility:public"],
+)