Replace legacy hooks [#3588545]

Problem/Motivation

In Drupal 11, hook implementations via functions in *.module files are deprecated. Hook classes with corresponding #[Hook('hook_whatever')] PHP attributes have to be used - all custom hook code (incl. preprocesses) should be updated for this.

Proposed resolution

All procedural hooks should be converted to hook classes

Remaining tasks

Create issue fork and MR to fix this issue
Convert all procedural legacy hooks to hook classes

User interface changes

n/a

API changes

All procedural hooks are converted to hook classes

Data model changes

n/a

Issue fork view_mode_switch-3588545

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3588545-replace-legacy-hooks changes, plain diff MR !50
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