message: packages/cli: remove reduntant theme provider from app template
diff: -import { CssBaseline, makeStyles, ThemeProvider } from '@material-ui/core';
  +import { makeStyles } from '@material-ui/core';
  import { createApp } from '@backstage/core';
  -import { lightTheme } from '@backstage/theme';
  import React, { FC } from 'react';
  import { BrowserRouter as Router } from 'react-router-dom';
  import * as plugins from './plugins';
  @@ -34,13 +33,9 @@ const App: FC<{}> = () => {
  useStyles();
  return (
  <AppProvider>
  - <ThemeProvider theme={lightTheme}>
  - <CssBaseline>
  <Router>
  <AppComponent />
  </Router>
  - </CssBaseline>
  - </ThemeProvider>
  </AppProvider>
  );
  };
  