use transform babel plugins instead of proposal

docs/porting-addons-to-v2.md

@@ -213,7 +213,7 @@ Now that we've separated the test-app and docs app concerns from the addon, we c
 4. `yarn add @embroider/addon-shim`. This is the only dependency a v2 addon needs (in order to interoperate with ember-cli.
 5. We're going to set up a default build pipeline for things like template colocation and decorator support. Install these dev dependencies:
 
-   `yarn add --dev @embroider/addon-dev rollup @rollup/plugin-babel @babel/core @babel/plugin-proposal-class-properties @babel/plugin-proposal-decorators`
+   `yarn add --dev @embroider/addon-dev rollup @rollup/plugin-babel @babel/core @babel/plugin-transform-class-properties @babel/plugin-proposal-decorators`
 
 6. Grab the [example babel config](https://github.com/embroider-build/embroider/blob/main/packages/addon-dev/sample-babel.config.json) and save it as `addon/babel.config.json`
    - If you addon requires template transforms in order to publish to a shareable format. Apply transforms using the `babel-plugin-ember-template-compilation`. View how to use this in the [example babel.config.js](https://github.com/embroider-build/embroider/blob/main/packages/addon-dev/sample-babel.config.js)

packages/addon-dev/sample-babel.config.js

@@ -18,6 +18,6 @@ module.exports = {
       },
     ],
     ['@babel/plugin-proposal-decorators', { legacy: true }],
-    '@babel/plugin-proposal-class-properties',
+    '@babel/plugin-transform-class-properties',
   ],
 };

packages/addon-dev/sample-babel.config.json

@@ -2,6 +2,6 @@
   "plugins": [
     "@embroider/addon-dev/template-colocation-plugin",
     ["@babel/plugin-proposal-decorators", { "legacy": true }],
-    "@babel/plugin-proposal-class-properties"
+    "@babel/plugin-transform-class-properties"
   ]
 }

packages/macros/tests/babel/macro-condition.test.ts

@@ -24,7 +24,7 @@ describe('macroCondition', function () {
     babelConfig(version: number) {
       let babelConfig = makeBabelConfig(version, config);
       if (version === 7) {
-        babelConfig.plugins.push('@babel/plugin-proposal-class-properties');
+        babelConfig.plugins.push('@babel/plugin-transform-class-properties');
       }
       babelConfig.filename = filename;
       return babelConfig;