create, but dont register, bp2build_deps mutator

This is the bulk of the "allowlist v2" feature. It will disable bp2build
generation for modules which have transitive dependencies without a
bazel build definition.

This CL includes this mutator, but doesn't register it as a bp2build
mutator (outside of a few unit tests). This allows us to easily iterate
on completion of this feature and ensure there are no launch blockers
before we finalize the change in AOSP.

Bug: 285631638
Test: Unit tests
Change-Id: Ifb0a079c409ca19b02cafa3fab2efa0d3deebc50
diff --git a/bp2build/bzl_conversion_test.go b/bp2build/bzl_conversion_test.go
index 402d4b0..645298f 100644
--- a/bp2build/bzl_conversion_test.go
+++ b/bp2build/bzl_conversion_test.go
@@ -95,6 +95,7 @@
         "bool_prop": attr.bool(),
         "bool_ptr_prop": attr.bool(),
         "dir": attr.string(),
+        "does_not_convert_to_bazel": attr.bool(),
         "embedded_prop": attr.string(),
         "int64_ptr_prop": attr.int(),
         # nested_props start
@@ -128,6 +129,7 @@
         "bool_prop": attr.bool(),
         "bool_ptr_prop": attr.bool(),
         "dir": attr.string(),
+        "does_not_convert_to_bazel": attr.bool(),
         "embedded_prop": attr.string(),
         "int64_ptr_prop": attr.int(),
         # nested_props start
@@ -161,6 +163,7 @@
         "bool_prop": attr.bool(),
         "bool_ptr_prop": attr.bool(),
         "dir": attr.string(),
+        "does_not_convert_to_bazel": attr.bool(),
         "embedded_prop": attr.string(),
         "int64_ptr_prop": attr.int(),
         # nested_props start