Replace annotation of plugins with corresponding PHP attributes

Problem/Motivation

From Drupal 10.3 on, plugins should use PHP attributes instead of a plugin annotations. See the following for more information:

• #3420981: Convert FieldType plugin discovery to attributes
• https://www.drupal.org/node/3229001
• https://www.drupal.org/node/3395575

So this should be changed for view_mode_switch related plugins once Drupal 10.2.x is not supported by the module anymore.

Proposed resolution

• Replace view_mode_switch module's plugin annotations with corresponding PHP attributes

Remaining tasks

• Create issue fork and MR to fix this issue

User interface changes

n/a

API changes

• view_mode_switch field type plugin will only be found by attribute discovery of field type plugins anymore
• view_mode_switch field formatter plugins will only be found by attribute discovery of field type plugins anymore
• view_mode_switch field widget plugin will only be found by attribute discovery of field type plugins anymore

Data model changes

n/a