Convert apex_available (for supported modules) to bazel tags.

The tags will then be read by an aspect applied from apex attributes to
validate that the deps are explicitly opt-in to the appropriate apex.

The semantics of this is the same as the Soong apex_available property.

This also adds the "base_apex_name" attr to override_apex conversion so
that apex_available checks continue to work on the non-Google and non-Go
apex names.

Test: presubmits
Fixes: 218841706
Change-Id: I19b3637da9aa47573b252d74f62b601fbdc3784d

apex/apex.go

@@ -2676,6 +2676,10 @@ func (o *OverrideApex) ConvertWithBp2build(ctx android.TopDownMutatorContext) {
 	}
 	attrs, props := convertWithBp2build(a, ctx)
 
+	// We just want the name, not module reference.
+	baseApexName := strings.TrimPrefix(baseApexModuleName, ":")
+	attrs.Base_apex_name = &baseApexName
+
 	for _, p := range o.GetProperties() {
 		overridableProperties, ok := p.(*overridableProperties)
 		if !ok {
@@ -3397,6 +3401,7 @@ type bazelApexBundleAttributes struct {
 	Package_name          *string
 	Logging_parent        *string
 	Tests                 bazel.LabelListAttribute
+	Base_apex_name        *string
 }
 
 type convertedNativeSharedLibs struct {