Rename ApexName to ApexVariationName

In preparation for reusing the same variation for multiple apexes,
rename ApexName to ApexVariationName.

Bug: 164216768
Test: all soong tests
Change-Id: I88f2c5b192ffa27acd38e01952d0cefd413222a0
diff --git a/java/java.go b/java/java.go
index d5375a5..10c6fd3 100644
--- a/java/java.go
+++ b/java/java.go
@@ -1680,7 +1680,7 @@
 		j.linter.compileSdkVersion = lintSDKVersionString(j.sdkVersion())
 		j.linter.javaLanguageLevel = flags.javaVersion.String()
 		j.linter.kotlinLanguageLevel = "1.3"
-		if j.ApexName() != "" && ctx.Config().UnbundledBuildApps() {
+		if j.ApexVariationName() != "" && ctx.Config().UnbundledBuildApps() {
 			j.linter.buildModuleReportZip = true
 		}
 		j.linter.lint(ctx)