Tag apex_set's 'set' config with `android:"path"`

This allows apex_set's set config to use other soong modules as a dependency

Bug:249169376
Change-Id: I8da20c6f474328d63d9aa3811f94e3e04b89ea4c
Test: Added a test case to check soong module assignment to the set field of an apks_set rule
diff --git a/apex/prebuilt.go b/apex/prebuilt.go
index 172a201..25ae5bf 100644
--- a/apex/prebuilt.go
+++ b/apex/prebuilt.go
@@ -840,17 +840,17 @@
 
 type ApexExtractorProperties struct {
 	// the .apks file path that contains prebuilt apex files to be extracted.
-	Set *string
+	Set *string `android:"path"`
 
 	Sanitized struct {
 		None struct {
-			Set *string
+			Set *string `android:"path"`
 		}
 		Address struct {
-			Set *string
+			Set *string `android:"path"`
 		}
 		Hwaddress struct {
-			Set *string
+			Set *string `android:"path"`
 		}
 	}