Vulkan: Improve shader compile error handling

[Pokechu22]

Two fairly minor improvements:

• Close the output stream on shader compile error before showing the panic alert: This fixes the file showing up as 0 bytes in Windows Explorer (although the file would still display properly when opened).
• Include the info log in the shader compile error panic alert: The other backends do this, and it is helpful for quickly identifying errors during development.

Here's what the warning looked like beforehand:

And here's the new warning:

And the relevant code on other backends, for reference:

dolphin/Source/Core/VideoBackends/OGL/ProgramShaderCache.cpp

Lines 357 to 376 in 2e01dc0

	if (compileStatus != GL_TRUE)
	{
	ERROR_LOG_FMT(VIDEO, "{} failed compilation:\n{}", prefix, info_log);
	std::string filename = VideoBackendBase::BadShaderFilename(prefix, num_failures++);
	std::ofstream file;
	File::OpenFStream(file, filename, std::ios_base::out);
	file << s_glsl_header << code << info_log;
	file << "\n";
	file << "Dolphin Version: " + Common::GetScmRevStr() + "\n";
	file << "Video Backend: " + g_video_backend->GetDisplayName();
	file.close();
	PanicAlertFmt("Failed to compile {} shader: {}\n"
	"Debug info ({}, {}, {}):\n{}",
	prefix, filename, g_ogl_config.gl_vendor, g_ogl_config.gl_renderer,
	g_ogl_config.gl_version, info_log);
	return false;
	}

dolphin/Source/Core/VideoBackends/D3DCommon/Shader.cpp

Lines 108 to 125 in 2e01dc0

	if (FAILED(hr))
	{
	static int num_failures = 0;
	std::string filename = VideoBackendBase::BadShaderFilename(target, num_failures++);
	std::ofstream file;
	File::OpenFStream(file, filename, std::ios_base::out);
	file.write(source.data(), source.size());
	file << "\n";
	file.write(static_cast<const char*>(errors->GetBufferPointer()), errors->GetBufferSize());
	file << "\n";
	file << "Dolphin Version: " + Common::GetScmRevStr() + "\n";
	file << "Video Backend: " + g_video_backend->GetDisplayName();
	file.close();
	PanicAlertFmt("Failed to compile {}: {}\nDebug info ({}):\n{}", filename, Common::HRWrap(hr),
	target, static_cast<const char*>(errors->GetBufferPointer()));
	return std::nullopt;
	}