Migrate remaining native rules for Bazel 9 compatibility

[dzbarsky]

Please incorporate the native-rule migration proposed in PR #174 so GoogleSQL does not require the language rules removed from Bazel 9. This adapts cloud-spanner-emulator#374 to GoogleSQL's own BUILD files.

Why this is needed

Bazel 9 removes the remaining built-in C++ rules and disables automatic loading of external language rules by default. A downstream project upgrading its root build to Bazel 9 must load GoogleSQL's packages with that Bazel version, regardless of GoogleSQL's own .bazelversion pin. Implicit rule references can therefore prevent package loading before compilation starts.

GoogleSQL master 289c4bc6cf6e134129a032ccb2e4f849e000279c still has implicit rules in bazel/farmhash.BUILD, bazel/icu.BUILD, the native_utils BUILD text, googlesql/common/BUILD, googlesql/parser/BUILD, the execute-query BUILD files, and examples/bazel/BUILD.bazel. execute_query_test also calls native.sh_test.

Requested change

Load the C++, Java, proto, and shell rules explicitly, add the required direct module dependencies, and provide the temporary --incompatible_autoload_externally fallback for unchanged third-party BUILD files. Keep Bazel 7.6.1 as the project's pinned version and include the separate Bazel example. GoogleSQL uses Textmapper; the emulator's JavaCC/JDK changes are not applicable.

GoogleSQL's .bazelrc is not inherited by consuming root modules. Those roots may still need the same autoload flag for third-party archives until those archives migrate; this PR does not claim to remove every downstream Bazel 9 compatibility requirement.

Validation and remaining limitation

Package-loading queries pass under Bazel 7.6.1 for the affected GoogleSQL packages, FarmHash/ICU/native_utils overlays, and the separate example module. A Bazel 9.0.0 consumer loads those packages with a test-only single_version_override selecting rules_swift 3.1.2.

Without that test-only override, Bazel 9 stops before package loading: grpc 1.81.1 requires rules_swift compatibility level 2, while bazel_tools requires compatibility level 3. That independent dependency conflict is not changed by this PR. These checks validate package loading, not compilation or runtime behavior.

I understand GoogleSQL does not accept external code contributions; the PR is a reference implementation for maintainers to incorporate through the internal development process.