docs: Create renamings.js to collect renamed API entries (google#5426)

Create a file scripts/migration/renamings.js to collect information about renamed API entries. Start by filling it with the renamings already done to blockly.js.

scripts/migration/renamings.js

@@ -0,0 +1,73 @@
+/**
+ * @license
+ * Copyright 2021 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * @fileoverview Collected information about modules and module
+ * exports that have been renamed between versions.
+ *
+ * For now this is a node module, not a goog.module.
+ */
+'use strict';
+
+/**
+ * Map from Blockly core version number to table of renamings made
+ * *since* that version was released (since we don't know for sure
+ * what the version number of the release that will incorporate those
+ * renamings will be yet).
+ * @type {Object<string, ?>}
+ */
+const renamings = {
+  '4.20201217.0': {
+    Blockly: {
+      exports: {
+        // bind/unbind events functions.  See PR #4642
+        EventData: {module: 'Blockly.eventHandling', export: 'Data'},
+        bindEvent_: {module: 'Blockly.browserEvents', export: 'bind'},
+        unbindEvent_: {module: 'Blockly.browserEvents', export: 'unbind'},
+        bindEventWithChecks_: {
+          module: 'Blockly.browserEvents',
+          export: 'conditionalBind',
+        },
+      },
+    }
+  },
+  '6.20210701.0': {
+    Blockly: {
+      exports: {
+        // Clipboard.  See PR #5237.
+        clipboardXml_: {module: 'Blockly.clipboard', export: 'xml'},
+        clipboardSource_: {module: 'Blockly.clipboard', export: 'source'},
+        clipboardTypeCounts_: {
+          module: 'Blockly.clipboard',
+          export: 'typeCounts',
+        },
+        copy: {module: 'Blockly.clipboard'},
+        paste: {module: 'Blockly.clipboard'},
+        duplicate: {module: 'Blockly.clipboard'},
+
+        // mainWorkspace.  See PR #5244.
+        mainWorkspace: {
+          module: 'Blockly.common',
+          get: 'getMainWorkspace',
+          set: 'setMainWorkspace',
+        },
+        getMainWorkspace: {module: 'Blockly.common'},
+
+        // parentContainer, draggingConnections.  See PR #5262.
+        parentContainer: {
+          module: 'Blockly.common',
+          get: 'getParentContainer',
+          set: 'setParentContainer',
+        },
+        setParentContainer: {module: 'Blockly.common'},
+        draggingConnections: {module: 'Blockly.common'},
+
+      },
+    },
+  },
+};
+
+exports.renamings = renamings;