Force UTF-8 as the process code page on Windows

On Windows, add a new "utf8.manifest" application manifest to Orbit,
OrbitService and all tests so that we force UTF-8 as the application
code page. With this change, the "A" variants of Windows APIs now
support UTF-8, which is great because we don't have to change API calls
to their "W" variant, saving a UTF-8 to UTF-16 string conversion in user
code. This also makes std::filesystem::path accept UTF-8 strings by
default (withouth explicit std::filesystem::u8path() call), and the
"std::filesystem::path::string()" also now outputs proper UTF-8 strings
out of the box, whitout calling "filesystem::path::u8string()".

References:
- microsoft/STL#909
- https://docs.microsoft.com/en-us/windows/apps/design/globalizing/use-utf8-code-page
- https://cmake.org/cmake/help/v3.4/release/3.4.html#other

From CMake's doc:
"CMake learned to honor *.manifest source files with MSVC tools.
Manifest files named as sources of .exe and .dll targets will be merged
with linker-generated manifests and embedded in the binary."

Tests: Newly added "UnicodeFileExists" in FileTest.cpp works out of the
box without modification to our "FileExists" function. This means that
"filesystem::path::exists()" can also be called directly with UTF-8
strings.

cmake/tests.cmake

@@ -34,6 +34,11 @@ function(register_test TEST_TARGET)
         $<TARGET_FILE_DIR:${TEST_TARGET}>/testdata/${TEST_TARGET})
     target_link_libraries(${TEST_TARGET} PRIVATE OrbitBase)
   endif()
+
+  if(WIN32)
+  # Use UTF-8 as the process code page.
+  target_sources(${TEST_TARGET} PRIVATE ${CMAKE_SOURCE_DIR}/src/WindowsManifest/utf8.manifest)
+  endif()
 endfunction()
 
 if(NOT TARGET GTest::GTest)

src/Orbit/CMakeLists.txt

@@ -33,6 +33,9 @@ if(WIN32)
                       "${CMAKE_CURRENT_SOURCE_DIR}/Orbit.rc.in" Orbit)
   target_sources(Orbit PRIVATE ${CMAKE_CURRENT_BINARY_DIR}/Orbit.rc)
 
+  # Use UTF-8 as the process code page.
+  target_sources(Orbit PRIVATE ${CMAKE_SOURCE_DIR}/src/WindowsManifest/utf8.manifest)
+
   # We have to wait for the OrbitQtTests to be finished building because
   # as part of this target also windeployqt is called which is also needed
   # by the Orbit target.

src/OrbitBase/FileTest.cpp

@@ -10,6 +10,7 @@
 #include "OrbitBase/ReadFileToString.h"
 #include "OrbitBase/Result.h"
 #include "OrbitBase/TemporaryFile.h"
+#include "OrbitBase/WindowsVersion.h"
 #include "OrbitBase/WriteStringToFile.h"
 #include "Test/Path.h"
 #include "TestUtils/TestUtils.h"
@@ -424,4 +425,24 @@ TEST(File, GetFileDateModified) {
   EXPECT_LE(file_time_or_error.value() - now, absl::Seconds(1));
 }
 
-}  // namespace orbit_base
+TEST(File, UnicodeFileExists) {
+  constexpr const char* kUnicodeFileName = "UnicodeFileName🚀.txt";
+  std::filesystem::path file_path = orbit_test::GetTestdataDir() / kUnicodeFileName;
+
+  // Call "FileExists" with a path containing a Unicode character.
+  auto file_exists = FileExists(file_path);
+  ASSERT_THAT(file_exists, HasNoError());
+  EXPECT_TRUE(file_exists.value()) << "Could not find unicode file path " << file_path.u8string()
+#ifdef __WIN32
+                                   << " " << orbit_base::GetWindowsVersionAsString().value()
+#endif
+      ;
+
+  // Call "FileExists" with "file_path.string()" which should be a valid UTF-8 string.
+  std::string unicode_file_path_as_string = file_path.string();
+  file_exists = FileExists(unicode_file_path_as_string);
+  ASSERT_THAT(file_exists, HasNoError());
+  EXPECT_TRUE(file_exists.value());
+}
+
+}  // namespace orbit_base

src/OrbitBase/testdata/UnicodeFileName🚀.txt

@@ -0,0 +1 @@
+🚀

src/Service/CMakeLists.txt

@@ -37,7 +37,16 @@ target_link_libraries(OrbitServiceLib PUBLIC
 endif()
 
 project(OrbitService)
-add_executable(OrbitService main.cpp)
+
+add_executable(OrbitService)
+
+target_sources(OrbitService PRIVATE main.cpp)
+
+if(WIN32)
+# Use UTF-8 as the process code page.
+target_sources(OrbitService PRIVATE ${CMAKE_SOURCE_DIR}/src/WindowsManifest/utf8.manifest)
+endif()
+
 target_link_libraries(OrbitService PRIVATE OrbitServiceLib)
 
 strip_symbols(OrbitService)

src/WindowsManifest/utf8.manifest

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
+<assembly manifestVersion="1.0" xmlns="urn:schemas-microsoft-com:asm.v1">
+  <application>
+    <windowsSettings>
+      <activeCodePage xmlns="http://schemas.microsoft.com/SMI/2019/WindowsSettings">UTF-8</activeCodePage>
+    </windowsSettings>
+  </application>
+</assembly>