Move URI list parsing to shared code

This will soon be used by the Wayland backend.

(cherry picked from commit ad4a9e42f0)

src/internal.h

@@ -775,6 +775,7 @@ 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);