Using JSpecify for and with Bazel

### Description of the feature request:

JSpecify would be very useful for:
* any project built with Bazel - but the special affordances for it in Bazel and rules_java are not documented.
* the Bazel project itself, especially now that IntelliJ warns on nullable type parameters for `ImmutableCollection`s by default.

### Which category does this issue belong to?

Java Rules

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

_No response_

### 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` ?

```text

```

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

_No response_

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

_No response_

The issue names JSpecify, Bazel, rules_java, and the Java Rules category but does not identify files, tests, or an entry point. Define the desired Bazel and rules_java affordances and the Bazel-project scope first; done cannot be determined from the current description.

Written by the indexing model from the issue text.