chore: Merge branch 'master' back into develop after v9.0.1 release

Merge changes made in the master branch since the v9.0.0 release
(specifically, updating the version number to 9.0.1 and correcting an
error in renamings.json5) so as to reduce the liklihood of merge
conflicts when we next release (by merging from develop to master).

There were conflicts in
* core/field_angle.ts
* core/field_dropdown.ts
* core/field_variable.ts

that were due to having cherry-picked changes from develop into master for
the 9.0.1 release; these were "resolved" by resetting those files to the
develop version, since the "changes" thereby lost were just adapting the
cherry-picks to fit code in master that had not had various intermediate
PRs applied to it yet.

Similarly, conflicts in blockly_compressed.js and .js.map were "resolved"
by restting those files; I note that we could do a rebuild to update
the pre-built files in develop but they will soon be deleted anyway,
and in any case rebuilding them would not make them the same as the
9.0.1 release as many other PRs have landed in the meantime.

A conflict in package-lock.json was resolved by resetting that file to the
develop version and then running npm install to update package-lock.json
with the change to the blockly version number.

package-lock.json

@@ -1,12 +1,12 @@
 {
   "name": "blockly",
-  "version": "9.0.0",
+  "version": "9.0.1",
   "lockfileVersion": 2,
   "requires": true,
   "packages": {
     "": {
       "name": "blockly",
-      "version": "9.0.0",
+      "version": "9.0.1",
       "license": "Apache-2.0",
       "dependencies": {
         "jsdom": "15.2.1"

package.json

@@ -1,6 +1,6 @@
 {
   "name": "blockly",
-  "version": "9.0.0",
+  "version": "9.0.1",
   "description": "Blockly is a library for building visual programming editors.",
   "keywords": [
     "blockly"

scripts/migration/renamings.json5

@@ -1360,7 +1360,7 @@
     {
       oldName: 'Blockly.PHP',
       newExport: 'phpGenerator',
-      newPath: 'Blockly.php',
+      newPath: 'Blockly.PHP',
     },
     {
       oldName: 'Blockly.Python',