Move URI list parsing to shared code

This will soon be used by the Wayland backend.

src/internal.h

@@ -996,6 +996,7 @@ void _glfwTerminateVulkan(void);
 const char* _glfwGetVulkanResultString(VkResult result);
 
 size_t _glfwEncodeUTF8(char* s, uint32_t codepoint);
+char** _glfwParseUriList(char* text, int* count);
 
 char* _glfw_strdup(const char* source);
 int _glfw_min(int a, int b);