cquery --output=proto: include complete configuration information

### Description of the feature request:

cquery's proto output models configurations at https://github.com/bazelbuild/bazel/blob/f309e0fc7fefa5d597db0b2dec7762e5523b69e7/src/main/protobuf/analysis_v2.proto#L177-L192.

This has basic metadata but doesn't include the configurations' contents (its `{flag: val}` map).

Add the full contents in to provider deeper ability for configuration analysis.

### What underlying problem are you trying to solve with this feature?

deeper ability to inspect and compare graph nodes without having to run `$ bazel config` again locally

### Which operating system are you running Bazel on?

_No response_

### What is the output of `bazel info release`?

_No response_

### If `bazel info release` returns `development version` or `(@non-git)`, tell us how you built Bazel.

_No response_

### What's the output of `git remote get-url origin; git rev-parse master; git rev-parse HEAD` ?

_No response_

### Have you found anything relevant by searching the web?

https://github.com/bazelbuild/bazel/issues/19058

### Any other information, logs, or outputs that you want to share?

_No response_

Start with the configuration model in src/main/protobuf/analysis_v2.proto and trace the cquery --output=proto path that produces it. Compare that output with bazel config to identify the complete {flag: val} contents; done means cquery proto output includes those contents for configuration analysis.

Written by the indexing model from the issue text.