Updated repository rules to notify users about non-reproducible repos.

[UebelAndre]

This change updates rules_rust repository rules to report when the rules are not guaranteed to be reproducible due to missing sha256 values when fetching Rust artifacts. A common case for this is when users request newer versions of Rust than the ones referenced in @rules_rust//rust:known_shas.bzl, thus leading to unnecessary downloads or potential security issues. After this PR, users will see warnings similar to when integrity is omitted from http_archive definitions

DEBUG: Rule 'rust_analyzer_1.77.1_tools' indicated that a canonical reproducible form can be obtained by modifying arguments sha256s = {"rust-src-1.77.1.tar.xz": "ad2064aa4a444ae35d55b8b57bec837b90c4f10fe6d721f8fce86d7a1992f607", "rustc-1.77.1-aarch64-apple-darwin.tar.xz": "8da1814eb8358236e88ceb155e32f0f34bbe71cb19cd9700c7eb40e675738d77"}
DEBUG: Repository rust_analyzer_1.77.1_tools instantiated at:
  /Users/user/rules_rust/WORKSPACE.bazel:7:25: in <toplevel>
  /Users/user/rules_rust/rust/repositories.bzl:202:10: in rust_register_toolchains
  /private/var/tmp/_bazel_user/76282c66b0dfe3c5cb9a230bdc913a52/external/bazel_tools/tools/build_defs/repo/utils.bzl:240:18: in maybe
  /Users/user/rules_rust/rust/repositories.bzl:737:45: in rust_analyzer_toolchain_repository
Repository rule rust_analyzer_toolchain_tools_repository defined at:
  /Users/user/rules_rust/rust/repositories.bzl:705:59: in <toplevel>
DEBUG: Rule 'rust_darwin_aarch64__aarch64-apple-darwin__stable_tools' indicated that a canonical reproducible form can be obtained by modifying arguments sha256s = {"rustc-1.77.1-aarch64-apple-darwin.tar.xz": "8da1814eb8358236e88ceb155e32f0f34bbe71cb19cd9700c7eb40e675738d77", "clippy-1.77.1-aarch64-apple-darwin.tar.xz": "343f125b0c05dd756e71992c04fb5a4a29ce705c50a739d76eb7f38b088103ac", "cargo-1.77.1-aarch64-apple-darwin.tar.xz": "c0249b6c247953cbe3b01e276988b6ca600aeba4e91332cd2ddaa0b7eee4dfb7", "llvm-tools-1.77.1-aarch64-apple-darwin.tar.xz": "dfee0aaed6b24d34362f229f2926e6b1805f2a8ec4a090c7c28837b82a9bdfd1", "rust-std-1.77.1-aarch64-apple-darwin.tar.xz": "3b5b71e40d934de25dcb553b9df28289d38640e6fa2654b42410f4cc8d9bed2a"}
DEBUG: Repository rust_darwin_aarch64__aarch64-apple-darwin__stable_tools instantiated at:
  /Users/user/rules_rust/WORKSPACE.bazel:7:25: in <toplevel>
  /Users/user/rules_rust/rust/repositories.bzl:230:14: in rust_register_toolchains
  /private/var/tmp/_bazel_user/76282c66b0dfe3c5cb9a230bdc913a52/external/bazel_tools/tools/build_defs/repo/utils.bzl:240:18: in maybe
  /Users/user/rules_rust/rust/repositories.bzl:1043:61: in rust_repository_set
  /Users/user/rules_rust/rust/repositories.bzl:601:36: in rust_toolchain_repository
Repository rule rust_toolchain_tools_repository defined at:
  /Users/user/rules_rust/rust/repositories.bzl:475:50: in <toplevel>

The above was produced by running bazel test //... after applying the following diff:

diff --git a/rust/private/common.bzl b/rust/private/common.bzl
index 52728fe7..c035ad5a 100644
--- a/rust/private/common.bzl
+++ b/rust/private/common.bzl
@@ -31,7 +31,7 @@ load(":providers.bzl", "CrateGroupInfo", "CrateInfo", "DepInfo", "DepVariantInfo
 #
 # Note: Code in `.github/workflows/crate_universe.yaml` looks for this line, if
 # you remove it or change its format, you will also need to update that code.
-DEFAULT_RUST_VERSION = "1.77.0"
+DEFAULT_RUST_VERSION = "1.77.1"

 DEFAULT_NIGHTLY_ISO_DATE = "2024-03-21"

closes #1825

[illicitonion]

Nice! Thanks!