Make theme_status_report compatible with drupal_render()

Problem/Motivation

In order to resolve #2009688: Replace theme() with drupal_render() in update module, theme_status_report needs to be updated to be compatible with drupal_render().

Proposed resolution

Update theme_status_report() and convert all implementations of theme('status_report') to the new drupal_render() approach.

Related Issues

• #2009688: Replace theme() with drupal_render() in update module
• Part of #2015147: [meta] Improve the DX of drupal_render() and renderable arrays