Support Bazel 8, remove deprecated rules_proto

Improve dependency management to support Bazel 8 properly, this is now working at least with bzlmod. - Update rules_fuzzing to fix version compatibility issue with protobuf - rules_proto is deprecated. Import rules directly from protobuf as is intended with Bazel 8. Update protobuf to 27.5 since 26.0 does not define the required rules. - Import fuzztest in bzlmod – this way WORKSPACE.bzlmod is now empty. - Cleanup: remove redundant absl/debugging:leak_check dependency from tcmalloc library