Add wonder-stuff-i18n package. (#216)

## Summary:
This moves the i18n logic out of Webapp and into Wonder Stuff so that it can be more-easily shared.

In the process I converted the code to use ES6 imports/exports and also use Flow types.

I had to add some logic to our build-settings so that we can generate bin scripts (since this is the first package to have them).

Issue: FEI-4434

## Test plan:
I confirmed the bin scripts worked by making a simple test file and then running `yarn build` in the root and then the following in `packages/wonder-blocks-i18n`:

```
packages/wonder-stuff-i18n (i18n-pkg) > ./dist/bin/gen-potfile.js foo.js
msgid ""
msgstr ""

#: foo.js:1
msgid "Test String"
msgstr ""

#: foo.js:3
#, python-format
msgid "Singular %(num)s"
msgid_plural "Plural %(num)s"
msgstr[0] ""
msgstr[1] ""

packages/wonder-stuff-i18n (i18n-pkg) > ./dist/bin/all-i18n-strings.js foo.js
Test String
Singular %(num)s (plural: Plural %(num)s)
```

Author: jeresig

Reviewers: kevinbarabash, jeresig

Required Reviewers: 

Approved By: kevinbarabash

Checks: ✅ Test (macOS-latest, 16.x), ✅ Test (macOS-latest, 12.x), ✅ Test (ubuntu-latest, 12.x), ✅ codecov/project, ✅ CodeQL, ✅ Lint, flow, and coverage check (ubuntu-latest, 16.x), ✅ gerald, ✅ Analyze (javascript), ✅ Prime node_modules cache for primary configuration (ubuntu-latest, 16.x), ⏭  dependabot

Pull Request URL: #216

.changeset/large-papayas-hammer.md

@@ -0,0 +1,6 @@
+---
+"@khanacademy/wonder-stuff-i18n": major
+"ws-dev-build-settings": patch
+---
+
+Add wonder-stuff-i18n package.

.eslintrc.js

@@ -32,6 +32,12 @@ module.exports = {
                 "max-lines": "off",
             },
         },
+        {
+            files: ["**/bin/**/*.js"],
+            rules: {
+                "no-console": "off",
+            },
+        },
     ],
     rules: {
         "new-cap": "off",

build-settings/rollup.config.js

@@ -8,6 +8,8 @@ import copy from "rollup-plugin-copy";
 import resolve from "@rollup/plugin-node-resolve";
 import replace from "@rollup/plugin-replace";
 import filesize from "rollup-plugin-filesize";
+import {preserveShebangs} from "rollup-plugin-preserve-shebangs";
+import rollupExecutable from "rollup-plugin-executable-output";
 
 const createBabelPresets = require("./create-babel-presets.js");
 const createBabelPlugins = require("./create-babel-plugins.js");
@@ -86,7 +88,7 @@ const getFormats = ({configFormats}) =>
  */
 const createConfig = (
     commandLineArgs,
-    {name, format, platform, file, plugins},
+    {name, format, platform, inputFile, file, plugins},
 ) => {
     const valueReplacementMappings = {
         __IS_BROWSER__: platform === "browser",
@@ -103,7 +105,7 @@ const createConfig = (
 
     const config = {
         output: createOutputConfig(name, format, file),
-        input: makePackageBasedPath(name, "./src/index.js"),
+        input: makePackageBasedPath(name, inputFile || "./src/index.js"),
         plugins: [
             // We don't want to do process.env.NODE_ENV checks in our main
             // builds. Our consumers should handle that. However, if we
@@ -235,6 +237,24 @@ const getPackageInfo = (commandLineArgs, pkgName) => {
             });
         }
     }
+
+    // Figure out if there are any scripts that we need to generate.
+    const binsPath = makePackageBasedPath(pkgName, "./src/bin");
+    if (fs.existsSync(binsPath)) {
+        const binFiles = fs.readdirSync(binsPath);
+
+        for (const binFile of binFiles) {
+            configs.push({
+                name: pkgName,
+                format: "cjs",
+                platform: "node",
+                file: `dist/bin/${binFile}`,
+                inputFile: `./src/bin/${binFile}`,
+                plugins: [preserveShebangs(), rollupExecutable()],
+            });
+        }
+    }
+
     return configs;
 };
 

flow-typed/npm/ancesdir_vx.x.x.js

@@ -0,0 +1,35 @@
+// flow-typed signature: 02e095fc2135e742ae3a993ce37b6294
+// flow-typed version: <<STUB>>/ancesdir_v1.1.0/flow_v0.176.0
+
+/**
+ * This is an autogenerated libdef stub for:
+ *
+ *   'ancesdir'
+ *
+ * Fill this stub out by replacing all the `any` types.
+ *
+ * Once filled out, we encourage you to share your work with the
+ * community by sending a pull request to:
+ * https://github.com/flowtype/flow-typed
+ */
+
+declare module 'ancesdir' {
+  declare module.exports: any;
+}
+
+/**
+ * We include stubs for each file inside this npm package in case you need to
+ * require those files directly. Feel free to delete any files that aren't
+ * needed.
+ */
+declare module 'ancesdir/dist' {
+  declare module.exports: any;
+}
+
+// Filename aliases
+declare module 'ancesdir/dist/index' {
+  declare module.exports: $Exports<'ancesdir/dist'>;
+}
+declare module 'ancesdir/dist/index.js' {
+  declare module.exports: $Exports<'ancesdir/dist'>;
+}