move all plugin tests out of babel-core and into their appropriate folders

packages/babel-plugin-transform-function-bind/test/fixtures/function-bind/bind/actual.js

@@ -0,0 +1,3 @@
+var f = ctx::ns.obj.func;
+var g = ::ns.obj.func;
+var h = new X::y;

packages/babel-plugin-transform-function-bind/test/fixtures/function-bind/bind/expected.js

@@ -0,0 +1,5 @@
+var _context;
+
+var f = (_context = ctx, ns.obj.func).bind(_context);
+var g = (_context = ns.obj).func.bind(_context);
+var h = (_context = new X(), y).bind(_context);