Use dependency injection for image styles in video formatters

Problem/Motivation

Both video formatters inject and store image-style entity storage, and use global service calls to build image-style options. PHPStan reports eight dependency-injection findings.

Steps to reproduce

1. Run PHPStan with the Drupal extension against both classes in src/Plugin/Field/FieldFormatter.
2. Observe the entity-storage injection, storage-property assignment and global service-call findings.

Proposed resolution

Inject the entity type manager and retrieve image-style storage when needed. Build the existing style options from that storage without version-dependent global calls.

Kernel tests pass on Drupal 10 and 11 for plugin creation, image-style options and summaries, including after serialization. All eight findings are resolved; two existing new static() warnings are outside this issue.

This follows the merged coding cleanup in #3628807. Compatibility with the other pending MRs has been checked.

Remaining tasks

Review and merge the MR.

API changes

Both constructors accept EntityTypeManagerInterface in place of image-style storage. The protected imageStyleStorage property becomes entityTypeManager. Custom instantiation or subclasses using these must be updated.