Isolate all TS stuff in hello package

test/hello-world-ts.test.ts

@@ -1,15 +0,0 @@
-process.env.CDS_TYPESCRIPT = 'true';
-import * as cds from '@sap/cds';
-
-//@ts-ignore
-const {GET} = cds.test.in(__dirname,'../hello').run('serve', 'world.cds');
-
-describe('Hello world!', () => {
-    afterAll(() => { delete process.env.CDS_TYPESCRIPT; });
-
-    it('should say hello with class impl from a typescript file', async () => {
-        const {data} = await GET`/say/hello(to='world')`
-        expect(data.value).toMatch(/Hello world.*typescript.*/i)
-    })
-
-})