Provide default names and titles for overrides

Problem/Motivation

Currently it's necessary to manually enter a machine name for each features override. Usually, though, a feature developer will want to use a naming convention. Also, the requirement for manual naming blocks automated override export, #1314662: Provide drush and UI methods for mass exporting overrides.

We need to support multiple or chained overrides to a given component, e.g., I install a distribution that includes an override of a view and I want to save additional changes to that view. So we need the ability for an override, or a set of overrides being generated, to have a custom name part so it won't conflict with other overrides of the same component.

Proposed resolution

Provide default names for override components. Likely this should be based on a configuration option with token support. Possible default for machine name:

[override_set_name]_[component_type]_[component_name]

where [override_set_name] is the configured name of a set of overrides to go into a new feature. E.g., If I'm generating an override of a view with machine name 'event' for my local install of open atrium at example.org and have configured the override_set_name to be 'example', the override would be: example_view_event.