Remove lazy declaration and proxy class for MIME type guessers

Problem/Motivation

Both the MIME Type Guesser service and the single implementation in core are marked as lazy:

  file.mime_type.guesser:
    class: Drupal\Core\File\MimeType\MimeTypeGuesser
    arguments: ['@stream_wrapper_manager']
    tags:
      - { name: service_collector, tag: mime_type_guesser, call: addMimeTypeGuesser }
    lazy: true
  file.mime_type.guesser.extension:
    class: Drupal\Core\File\MimeType\ExtensionMimeTypeGuesser
    arguments: ['@Drupal\Core\File\MimeType\MimeTypeMapInterface']
    tags:
      - { name: mime_type_guesser }
    lazy: true

Neither of these services are expensive to instantiate; the stream wrapper manager will be initialised anyway, and injecting the mime_type_guesser services via a tagger iterator will mean that the individual guessers will only be instantiated when needed (and if a guesser returns early, the later ones will not be needed at all).

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet