Tests: Consolidate inputs for MemberImportVisibility tests.

NFC.

Author: tshortli

test/NameLookup/Inputs/MemberImportVisibility/Bridging.h

@@ -0,0 +1,9 @@
+@import Categories_A;
+
+@interface X (BridgingHeader)
+- (void)fromBridgingHeader;
+@end
+
+struct StructInBridgingHeader {
+  int member;
+};