Add global metrics on top of Doctrine page

[raziel057]

As the toolbar is not displayed any more on top of the profiler with Symfony 3.x, we don't have direct information about:

• the count of database queries
• the global query time
• the count of invalid entities

I think this information could be displayed on top of the page as global query metrics, like global metrics on other pages in the Web Profiler.

[raziel057]

Here is the result:

[mikeSimonson]

@raziel057 Thanks