Fix LineLength for @todo comments

Problem/Motivation

Part of #2572709: [meta] Fix 'Drupal.Files.LineLength' coding standard

Steps to reproduce

Find issues in each group by using phpcs --standard=core/phpcs.xml.dist --report-width=250 --report=code > a.txt and then searching those results

Proposed resolution

Wrap @todo comments at 80 col.

Find issues in each group by

1. Add <rule ref="Drupal.Files.LineLength"/> to phpcs.xml.dist
2. Run phpcs --standard=core/phpcs.xml.dist --report-width=250 --report=code > a.txt
3. Search for @todo in a.txt/li>

It is not possible to enforce a change for this with phpcs.xml.disl

Remaining tasks

User interface changes

Introduced terminology

API changes

Data model changes

Release notes snippet