Only remove type imports

ember-cli uses `babel-remove-types` to remove types from .gts files and if some of the imported references are only used in the `<template>` context, babel assumes they are unused and removes them.

By enabling the `onlyRemoveTypeImports` option of `@babel/plugin-transform-typescript` those imports are now no longer stripped.

Co-Authored-By: Bert De Block <[email protected]>

src/index.ts

@@ -4,7 +4,7 @@ import { format, Options as PrettierOptions } from 'prettier';
 
 // @ts-expect-error We're only importing so we can create a config item, so we don't care about types
 import bts from '@babel/plugin-transform-typescript';
-const babelTsTransform = createConfigItem(bts);
+const babelTsTransform = createConfigItem([bts, { onlyRemoveTypeImports: true }]);
 
 // @ts-expect-error We're only importing so we can create a config item, so we don't care about types
 import bsd from '@babel/plugin-syntax-decorators';

test/index.test.ts

@@ -123,6 +123,19 @@ export default class Foo extends Component {
     this.prop2 = prop2;
   }
 }
+`;
+    expect(await removeTypes(contents)).toEqual(expected);
+  });
+
+  it("doesn't remove unused imports", async () => {
+    const contents = `import Foo from 'foo';
+
+export default class Baz {}
+`;
+
+    const expected = `import Foo from 'foo';
+
+export default class Baz {}
 `;
     expect(await removeTypes(contents)).toEqual(expected);
   });