Fix path conflicts in chip_data_model in some projects

The chip_data_model template builds a library that contains 2 files
named encoder.cpp and two files name attribute-size.cpp.

While this is not a problem with pigweed's toolchain definitions because
different directories are used, it can cause a path conflict if a
project defines a toolchain that places all of a library's .o files in
the same directory:

ERROR at //third_party/connectedhomeip/repo/src/app/chip_data_model.gni:59:3: Duplicate object file
  source_set(_data_model_name) {
  ^-----------------------------
The target //third_party/connectedhomeip/repo/src/controller/data_model:data_model
generates two object files with the same name:
  obj/third_party/connectedhomeip/repo/src/controller/data_model/data_model/attribute-size.o

Rename some files so that all files in the same library have distinct
filenames, which should be compatible with most reasonable toolchain
definitions.

Change-Id: I75f755cd4231563a57eca1e5286527c9ea88149e

src/app/BUILD.gn

@@ -91,7 +91,7 @@ static_library("app") {
     "ReadClient.cpp",
     "ReadHandler.cpp",
     "decoder.cpp",
-    "encoder.cpp",
+    "encoder-common.cpp",
     "reporting/Engine.cpp",
     "reporting/Engine.h",
   ]

src/app/chip_data_model.gni

@@ -93,7 +93,7 @@ template("chip_data_model") {
       "${_app_root}/clusters/zll-level-control-server/zll-level-control-server.h",
       "${_app_root}/clusters/zll-on-off-server/zll-on-off-server.h",
       "${_app_root}/clusters/zll-scenes-server/zll-scenes-server.h",
-      "${_app_root}/encoder.cpp",
+      "${_app_root}/encoder-common.cpp",
       "${_app_root}/reporting/reporting-default-configuration.cpp",
       "${_app_root}/reporting/reporting-tokens.h",
       "${_app_root}/reporting/reporting.cpp",
@@ -102,7 +102,7 @@ template("chip_data_model") {
       "${_app_root}/util/af-event.cpp",
       "${_app_root}/util/af-main-common.cpp",
       "${_app_root}/util/attribute-list-byte-span.cpp",
-      "${_app_root}/util/attribute-size.cpp",
+      "${_app_root}/util/attribute-size-util.cpp",
       "${_app_root}/util/attribute-storage.cpp",
       "${_app_root}/util/attribute-table.cpp",
       "${_app_root}/util/binding-table.cpp",