Have ConvertWBp2build use Bp2buildMutatorContext

This no-op refactoring facilitates some upcoming functional changes for
"bp2build allowlist v2". The work requires that the bp2build conversion
mutator be changed from a TopDown mutator to a BottomUp mutator.
Refactoring all bp2build-related methods so that they use Bp2buildMutatorContext
makes it easier to make this functional change without touching tens of
files and multiple projects.

Bug: 285631638
Test: m bp2build
Change-Id: I3d1ef3064146e959c6f0dc315350fc9764bf2bd2
diff --git a/android/bazel_test.go b/android/bazel_test.go
index 15d3a6b..e0145b5 100644
--- a/android/bazel_test.go
+++ b/android/bazel_test.go
@@ -469,7 +469,7 @@
 	return m
 }
 
-func (m *mixedBuildModule) ConvertWithBp2build(ctx TopDownMutatorContext) {
+func (m *mixedBuildModule) ConvertWithBp2build(ctx Bp2buildMutatorContext) {
 }
 
 func (m *mixedBuildModule) DepsMutator(ctx BottomUpMutatorContext) {