Ruby: Change how we pull in shared/tree-sitter-extractor dependency

Previously, we pulled in the shared tree-sitter extractor via a `git`
dependency in `Cargo.toml` to address a `rules_rust` limitation (no `path`
dependencies outside of the cargo workspace)). This was a problem,
as that means we're cloning `github/codeql` _again_ for the build, which is
quite slow.

I found another way that is faster, and still produces correct builds
for both `cargo`` and `rules_rust`:
* Cargo depends on a fake crate that has the same dependencies as the real crate (thanks to `sync-files.py`). Therefore, cargo pulls in the right dependencies into the lockfile, which bazel targets
* For local builds, we override the path to that dependency in a cargo config, so we're pulling in the correct code
* rules_rust only uses `path` dependencies for collecting transitive dependencies, it never pulls in the code from there. So far that, we manually provide a `BUILD.bazel` file for the shared extractor, and depend on that.

config/identical-files.json

@@ -364,5 +364,9 @@
   "Python model summaries test extension": [
     "python/ql/test/library-tests/dataflow/model-summaries/InlineTaintTest.ext.yml",
     "python/ql/test/library-tests/dataflow/model-summaries/NormalDataflowTest.ext.yml"
+  ],
+  "shared tree-sitter extractor cargo.toml": [
+    "shared/tree-sitter-extractor/Cargo.toml",
+    "ruby/extractor/codeql-extractor-fake-crate/Cargo.toml"
   ]
 }