Swift: add integration test for multiple modules

Author: redsun82

swift/integration-tests/posix-only/partial-modules/Modules.expected

@@ -0,0 +1,4 @@
+| file://:0:0:0:0 | A |
+| file://:0:0:0:0 | B |
+| file://:0:0:0:0 | main |
+| file://:0:0:0:0 | partial_modules |

swift/integration-tests/posix-only/partial-modules/Modules.ql

@@ -0,0 +1,5 @@
+import swift
+
+from ModuleDecl decl
+where not decl.isBuiltinModule() and not decl.isSystemModule()
+select decl