Rename all proposal plugins to -proposal- from -transform- (#6570)

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/assignment-expression/actual.js

@@ -0,0 +1,4 @@
+({ a1 } = c1);
+({ a2, ...b2 } = c2);
+
+console.log({ a3, ...b3 } = c3);

packages/babel-plugin-proposal-object-rest-spread/test/fixtures/object-rest/assignment-expression/expected.js

@@ -0,0 +1,14 @@
+var _c2;
+
+({
+  a1
+} = c1);
+var _c = c2;
+({
+  a2
+} = _c);
+b2 = babelHelpers.objectWithoutProperties(_c, ["a2"]);
+_c;
+console.log((_c2 = c3, ({
+  a3
+} = _c2), b3 = babelHelpers.objectWithoutProperties(_c2, ["a3"]), _c2));