Fix incorrect use of word 'component' in locale module

Problem/Motivation

Locale module uses the word 'component' in both docs and code to mean different things, and most if not all of them are wrong.

Here's a sample:

  /**
   * Get all configuration names and folders for a list of modules or themes.
   *
   * @param string $type
   *   Type of components: 'module' | 'theme' | 'profile'
   * @param array $list
   *   Array of theme or module names.
   *
   * @return array
   *   Configuration names provided by that component. In case of language
   *   module this list is extended with configured languages that have
   *   predefined names as well.
   */
  public function getComponentNames($type, array $list) {

The docblock first line says:

> Get all configuration names

The method returns names of configuration objects. But it's called 'getComponentNames' -- are components configuration objects? I don't think anywhere else calls them that.

The parameter docs says:

> * Type of components: 'module' | 'theme' | 'profile'

and the @return says:

> Configuration names provided by that component

So components are module/theme/profiles?

We're now using the word 'component' to mean two different things!

There are other places in the module that do this too, such as this comment:

      // Update active configuration copies of all prior shipped configuration if
      // they are still English. It is not enough to change configuration shipped
      // with the components just installed, because installing a component such
      // as views may bring in default configuration from prior components.

Steps to reproduce

Proposed resolution

Replace the word 'component' with either:

- 'configuration object' -- this is what the core config component calls them
- 'extension'

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet