Sema: rework @fieldParentPtr to accept a pointer type

There is no way to know the expected parent pointer attributes (most
notably alignment) from the type of the field pointer, so provide them
in the first argument.

test/cases/compile_errors/invalid_bit_pointer.zig

@@ -0,0 +1,13 @@
+comptime {
+    _ = *align(1:32:4) u8;
+}
+comptime {
+    _ = *align(1:25:4) u8;
+}
+
+// error
+// backend=stage2
+// target=native
+//
+// :2:18: error: packed type 'u8' at bit offset 32 starts 0 bits after the end of a 4 byte host integer
+// :5:18: error: packed type 'u8' at bit offset 25 ends 1 bits after the end of a 4 byte host integer