Add rust toolchain to fix rustfmt crosscompilation error

[schreibwsag]

bazel build //... --config=target_config_3 leads to the following error:

ERROR: Analysis of target '//:format.fix_Rust_with_rustfmt' failed; build aborted: Analysis failed

bazel fails to find a suitable rust toolchain when crosscompiling.

Fix: register rust toolchains in MODULE.bazel (taken over from inc_security_crypto_valeo_pitch)

[github-actions]

License Check Results

🚀 The license check job ran with the Bazel command:

bazel run --lockfile_mode=error //:license-check

Status: ⚠️ Needs Review

Click to expand output

[License Check Output]
2026/05/28 21:39:58 Downloading https://releases.bazel.build/8.3.0/release/bazel-8.3.0-linux-x86_64...
Extracting Bazel installation...
Starting local Bazel server (8.3.0) and connecting to it...
INFO: Invocation ID: 95702fd9-c9a9-47fe-a683-70f481354bb8
Computing main repo mapping: 
Computing main repo mapping: 
Computing main repo mapping: 
DEBUG: Rule 'abseil-cpp+' indicated that a canonical reproducible form can be obtained by modifying arguments integrity = "sha256-m3oGQwXp/ZTRJP+mzDWFkutCtdpYj7TgfQklSqQAhts="
DEBUG: Repository abseil-cpp+ instantiated at:
  <builtin>: in <toplevel>
Repository rule http_archive defined at:
  /home/runner/.bazel/external/bazel_tools/tools/build_defs/repo/http.bzl:394:31: in <toplevel>
Computing main repo mapping: 
DEBUG: Rule 'protobuf+' indicated that a canonical reproducible form can be obtained by modifying arguments integrity = "sha256-w6Cp7OiTLjHDtzbi2xixxC5wcM2biBOIsm0BqnHiTKI="
DEBUG: Repository protobuf+ instantiated at:
  <builtin>: in <toplevel>
Repository rule http_archive defined at:
  /home/runner/.bazel/external/bazel_tools/tools/build_defs/repo/http.bzl:394:31: in <toplevel>
Computing main repo mapping: 
DEBUG: Rule 'grpc+' indicated that a canonical reproducible form can be obtained by modifying arguments integrity = "sha256-CvN7gAlTEwtHwHW1ZoPuYL3D7aPDf8YAQZP1tWl1ggQ="
DEBUG: Repository grpc+ instantiated at:
  <builtin>: in <toplevel>
Repository rule http_archive defined at:
  /home/runner/.bazel/external/bazel_tools/tools/build_defs/repo/http.bzl:394:31: in <toplevel>
Computing main repo mapping: 
Computing main repo mapping: 
Computing main repo mapping: 
WARNING: For repository 'score_bazel_platforms', the root module requires module version score_bazel_platforms@0.1.1, but got score_bazel_platforms@0.1.2 in the resolved dependency graph. Please update the version in your MODULE.bazel or set --check_direct_dependencies=off
WARNING: For repository 'rules_cc', the root module requires module version rules_cc@0.2.16, but got rules_cc@0.2.17 in the resolved dependency graph. Please update the version in your MODULE.bazel or set --check_direct_dependencies=off
WARNING: For repository 'flatbuffers', the root module requires module version flatbuffers@25.2.10, but got flatbuffers@25.12.19 in the resolved dependency graph. Please update the version in your MODULE.bazel or set --check_direct_dependencies=off
Computing main repo mapping: 
Computing main repo mapping: 
Computing main repo mapping: 
Loading: 
Loading: 1 packages loaded
Loading: 1 packages loaded
    currently loading: 
Loading: 1 packages loaded
    currently loading: 
WARNING: Target pattern parsing failed.
ERROR: Skipping '//:license-check': no such target '//:license-check': target 'license-check' not declared in package '' defined by /home/runner/work/inc_security_crypto/inc_security_crypto/BUILD
ERROR: no such target '//:license-check': target 'license-check' not declared in package '' defined by /home/runner/work/inc_security_crypto/inc_security_crypto/BUILD
INFO: Elapsed time: 16.559s
INFO: 0 processes.
ERROR: Build did NOT complete successfully
ERROR: Build failed. Not running target

[github-actions]

The created documentation from the pull request is available at: docu-html

[pahmann]

Within other S-CORE modules rust toolchain is added in a different way.

Examples are:
https://github.com/eclipse-score/feo/blob/main/MODULE.bazel#L125
https://github.com/eclipse-score/persistency/blob/main/MODULE.bazel#L47
https://github.com/eclipse-score/baselibs_rust/blob/main/MODULE.bazel#L36

It makes sense to keep it aligned with the style of other repos unless there is a specific reason not to follow.

[schreibwsag]

Yes, it makes sense to keep it aligned with the style used in other repos. My intention
is to follow the baselib rust example. There is one reason why I did not do it yet: There
is a pitch by Valeo (https://github.com/Valeo-S-CORE-Organization/inc_security_crypto_valeo_pitch)
which will be pulled into this repo. I thought to make this easier, I take the rust toolchain
definition from the valeo repo. When this is pulled, we can change to the baselib_rust
style. Hope this is acceptable.

[schreibwsag]

I updated the PR. Hope it is OK. Thank you for giving me the examples.

[schreibwsag]

tidy + buildifier formatting applied, and all checks pass.