Add boost.cobalt library

[hgad]

boost.cobalt was recently added to Boost 1.84.0. Even though rules_boost has updated the underlying boost dependency to 1.84.0, I still cannot depend on the boost.cobalt library.

I updated the http_archive rule to depend on the latest rules_boost commit:

http_archive(
    name = "com_github_nelhage_rules_boost",
    strip_prefix = "rules_boost-e72eb259976357f6e82f4d74d74a7c12d1c3776d",
    url = "https://github.com/nelhage/rules_boost/archive/e72eb259976357f6e82f4d74d74a7c12d1c3776d.tar.gz",
)

and updated my binary's rule to depend on @boost//:cobalt:

cc_binary(
    name = "main_bin",
    srcs = ["main.cpp"],
    features = ["fully_static_link"],
    visibility = ["//visibility:public"],
    deps = [
        "@boost//:cobalt",
        ...
    ],
)

but I get the following errors:

DEBUG: Rule 'com_github_nelhage_rules_boost' indicated that a canonical reproducible form can be obtained by modifying arguments sha256 = "1ef96e5c4c7c05024e60dc5927f7c1f39c692530d1a396f0968ce1715cd00df4"
DEBUG: Repository com_github_nelhage_rules_boost instantiated at:
  /workspaces/workspace/WORKSPACE.bazel:9:13: in <toplevel>
Repository rule http_archive defined at:
  /home/vscode/.cache/bazel/_bazel_vscode/6516b5a3aaa4066f3b18ab2a8c6133fe/external/bazel_tools/tools/build_defs/repo/http.bzl:372:31: in <toplevel>
ERROR: /workspaces/workspace/BUILD.bazel:5:10: no such target '@boost//:cobalt': target 'cobalt' not declared in package '' defined by /home/vscode/.cache/bazel/_bazel_vscode/6516b5a3aaa4066f3b18ab2a8c6133fe/external/boost/BUILD.bazel (Tip: use `query "@boost//:*"` to see all the targets in that package) and referenced by '//services/main:main_bin'
ERROR: Analysis of target '//services/main:main' failed; build aborted: 
INFO: Elapsed time: 15.822s
INFO: 0 processes.
FAILED: Build did NOT complete successfully (203 packages loaded, 9766 targets configured)

Also, not sure what this "canonical reproducible form" means.