Include the product version as an alias when generating xcode_version targets

This allows passing `--xcode_version=$XCODE_PRODUCT_BUILD_VERSION` in the context of an Xcode shell script build phase

Closes #12563.

PiperOrigin-RevId: 345763331
diff --git a/tools/osx/xcode_configure.bzl b/tools/osx/xcode_configure.bzl
index e43e161..5b14fcb 100644
--- a/tools/osx/xcode_configure.bzl
+++ b/tools/osx/xcode_configure.bzl
@@ -74,7 +74,7 @@
     build_contents += "xcode_version(\n  name = '%s'," % name
     build_contents += "\n  version = '%s'," % version
     if aliases:
-        build_contents += "\n  aliases = [%s]," % " ,".join(decorated_aliases)
+        build_contents += "\n  aliases = [%s]," % ", ".join(decorated_aliases)
     if ios_sdk_version:
         build_contents += "\n  default_ios_sdk_version = '%s'," % ios_sdk_version
     if tvos_sdk_version:
@@ -231,7 +231,7 @@
         if (version.startswith(default_xcode_version) and
             version.endswith(default_xcode_build_version)):
             default_xcode_target = target_label
-    buildcontents += "xcode_config(name = 'host_xcodes',"
+    buildcontents += "xcode_config(\n  name = 'host_xcodes',"
     if target_names:
         buildcontents += "\n  versions = [%s]," % ", ".join(target_names)
     if not default_xcode_target and target_names:
@@ -242,7 +242,7 @@
         buildcontents += "\n  default = %s," % default_xcode_target
 
     buildcontents += "\n)\n"
-    buildcontents += "available_xcodes(name = 'host_available_xcodes',"
+    buildcontents += "available_xcodes(\n  name = 'host_available_xcodes',"
     if target_names:
         buildcontents += "\n  versions = [%s]," % ", ".join(target_names)
     if default_xcode_target: