adding entry point to soft driver, adding C test

src/vulkan/lib.zig

@@ -1,5 +1,7 @@
 const std = @import("std");
 
+pub const icd = @import("icd.zig");
+
 pub const Instance = @import("Instance.zig");
 pub const PhysicalDevice = @import("PhysicalDevice.zig");