建议升级下bazel

bazel应该是目前最有前途的cpp构建体系
brpc是支持bazel的，只是版本比较低好像6
目前最新的bazel 7 支持https://registry.bazel.build/
有比较完善的包依赖，这样会让brpc用起来更加方便，新增依赖的库就不用自己整了。

Start by inspecting brpc's current Bazel configuration and dependency declarations to identify the supported Bazel version and existing external-library setup. Check how the project builds and tests with that configuration. Done means Bazel 7 support is documented and the project builds and its tests pass using the updated dependency mechanism.

Written by the indexing model from the issue text.