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/xml/xml.go b/xml/xml.go
index 20a26f5..65fe12a 100644
--- a/xml/xml.go
+++ b/xml/xml.go
@@ -145,7 +145,7 @@
 	Schema            *string
 }
 
-func (p *prebuiltEtcXml) ConvertWithBp2build(ctx android.TopDownMutatorContext) {
+func (p *prebuiltEtcXml) ConvertWithBp2build(ctx android.Bp2buildMutatorContext) {
 	baseAttrs, convertible := p.PrebuiltEtc.Bp2buildHelper(ctx)
 
 	if !convertible {