Use canonical repo name for aspects

[cameron-martin]

Currently when running gen_rust_project, the aspect given to bazel has the canonical repo name but only a single @. This does not work with bzlmod, since it tries to resolve this using the repository mappings, and complains that the repository does not exist:

ERROR: Unable to find package for @@[unknown repo 'rules_rust~0.38.0' requested from @@]//rust:defs.bzl: The repository '@@[unknown repo 'rules_rust~0.38.0' requested from @@]' could not be resolved: No repository visible as '@rules_rust~0.38.0' from main repository.
ERROR: Analysis of aspects '[@@[unknown repo 'rules_rust~0.38.0' requested from @@]//rust:defs.bzl%rust_analyzer_aspect] with parameters {} on //prost:prost_toolchain_impl' failed; build aborted: Unable to find package for @@[unknown repo 'rules_rust~0.38.0' requested from @@]//rust:defs.bzl: The repository '@@[unknown repo 'rules_rust~0.38.0' requested from @@]' could not be resolved: No repository visible as '@rules_rust~0.38.0' from main repository.

This adds an extra @, so that the repository in the label is of canonical form.

Fixes #2449

[illicitonion]

Thanks! Could you add a test which fails before and passes after this change? We have some tests in https://github.com/bazelbuild/rules_rust/blob/main/examples/bzlmod/hello_world/BUILD.bazel for testing similar things, or can add extra run_targets to

rules_rust/.bazelci/presubmit.yml

Lines 641 to 656 in 649b32d

	ubuntu2004_bzlmod_bcr:
	name: bzlmod BCR presubmit
	platform: ubuntu2004
	working_directory: examples/bzlmod/hello_world
	run_targets:
	- "//third-party:vendor"
	test_targets:
	- "//..."
	macos_bzlmod_bcr:
	name: bzlmod BCR presubmit
	platform: macos
	working_directory: examples/bzlmod/hello_world
	run_targets:
	- "//third-party:vendor"
	test_targets:
	- "//..."

and

rules_rust/.bcr/presubmit.yml

Lines 10 to 11 in 649b32d

	run_targets:
	- "//third-party:vendor"

if we need to be invoking bazel run explicitly.

[cameron-martin]

Adding a regular bazel test is trickier because gen_rust_project needs to invoke bazel in the same workspace that the tool is built from. I've added these to run_targets instead.

[illicitonion]

Thanks!