Allow inheritance of `.bazelrc` snippets/flags across projects

### Description of the feature request:

One of the side-effects of incompatible Bazel flags in the Bazel ecosystem is that some projects *require* certain incompatible flags to be set in order for the project to build at all. As middleware, managing these flags can be particularly tricky since you may require different incompatible flags depending on the version of your dependencies, and you also may prescribe your own required flags. These are forked in downstream users projects, and they may accidentally diverge in ways that cause subtle or confusing breakages as updates are rolled out. Because there's no way to `import` .bazelrc snippets from external dependencies, there's virtually no solution for inheritance at all and you just have to manually manage your own project's .bazelrc and hope for the best.

Perhaps the right way to handle this is to integrate it into bzlmod, as that mechanism strives to address similar problems that existed in WORKSPACE files. Admittedly, this would likely be a massive undertaking to design and implement.

### Which category does this issue belong to?

External Dependency

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

Inconsistencies in `.bazelrc` requirements across dependent projects.

### 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 HEAD` ?

_No response_

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

_No response_

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

_No response_

Start by reading the issue's discussion about importing .bazelrc snippets and possible bzlmod integration. No source files, tests, or entry points are named; the work is not ready for a newcomer until the design, affected components, and acceptance criteria are defined.

Written by the indexing model from the issue text.