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_paths.go b/android/bazel_paths.go
index 86829ce..ac862d4 100644
--- a/android/bazel_paths.go
+++ b/android/bazel_paths.go
@@ -585,7 +585,7 @@
 // For the first two cases, they are defined using the label attribute. For the third case,
 // it's defined with the string attribute.
 func BazelStringOrLabelFromProp(
-	ctx TopDownMutatorContext,
+	ctx Bp2buildMutatorContext,
 	propToDistinguish *string) (bazel.LabelAttribute, bazel.StringAttribute) {
 
 	var labelAttr bazel.LabelAttribute