Use dot instead of colon as separator of custom part.

This is done becase ':' is already used as a separator between package
and type in a full resource name. So if we use ':' it will be consfusing
for custom resource types: com.my.package:layout:2/myLayout ->
com.my.package:layout.2/myLayout.

DD: go/custom-resource-types-in-aapt2

Bug: b/215108200
Test: Resource_test
Change-Id: Ieed256e4376abe0a3788d8198110bef189b55740
diff --git a/tools/aapt2/Resource_test.cpp b/tools/aapt2/Resource_test.cpp
index 2c55d1d..01d3c84 100644
--- a/tools/aapt2/Resource_test.cpp
+++ b/tools/aapt2/Resource_test.cpp
@@ -135,13 +135,13 @@
   type = ParseResourceNamedType("layout");
   EXPECT_THAT(type, Optional(Eq(ResourceNamedType("layout", ResourceType::kLayout))));
 
-  type = ParseResourceNamedType("layout:2");
-  EXPECT_THAT(type, Optional(Eq(ResourceNamedType("layout:2", ResourceType::kLayout))));
+  type = ParseResourceNamedType("layout.2");
+  EXPECT_THAT(type, Optional(Eq(ResourceNamedType("layout.2", ResourceType::kLayout))));
 
-  type = ParseResourceNamedType("layout:another");
-  EXPECT_THAT(type, Optional(Eq(ResourceNamedType("layout:another", ResourceType::kLayout))));
+  type = ParseResourceNamedType("layout.another");
+  EXPECT_THAT(type, Optional(Eq(ResourceNamedType("layout.another", ResourceType::kLayout))));
 
-  type = ParseResourceNamedType("layout:");
+  type = ParseResourceNamedType("layout.");
   EXPECT_THAT(type, Eq(std::nullopt));
 
   type = ParseResourceNamedType("layout2");