How is the backend's Component Manager grid rendered?

AngularJS template

It is rendered by the setup/view/magento/setup/component-grid.phtml AngularJS template.

AngularJS module

The component-grid.phtml template is called by the setup/pub/magento/setup/component-grid.js AngularJS module.

The module queries the components collection from the server part and assign the query result to the components variable of the template:

Server part: \Magento\Setup\Controller\ComponentGrid::componentsAction()

See also:

There is no more «Component Manager» in Magento 2.2: it has been replaced by «Extension Manager» and «Module Manager».