Fix the issues reported by phpcs

Problem/Motivation

FILE: ...l/vb/d_cont/add_to_calendar/tests/src/Functional/AddToCalendarBaseTest.php
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FOUND 0 ERRORS AND 1 WARNING AFFECTING 1 LINE
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47 | WARNING | Unused variable $entity_type_manager.
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FILE: ...ml/vb/d_cont/add_to_calendar/tests/src/Kernel/AddToCalendarDisplayTest.php
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FOUND 9 ERRORS AND 2 WARNINGS AFFECTING 8 LINES
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5 | ERROR | [x] Non-namespaced classes/interfaces/traits should not be
| | referenced with use statements
6 | ERROR | [x] Non-namespaced classes/interfaces/traits should not be
| | referenced with use statements
12 | WARNING | [x] Unused use statement
12 | ERROR | [x] Non-namespaced classes/interfaces/traits should not be
| | referenced with use statements
46 | ERROR | [ ] The array declaration extends to column 116 (the limit is
| | 80). The array content should be split up over multiple
| | lines
78 | WARNING | [x] A comma should follow the last multiline array item.
| | Found: 'full_html'
87 | ERROR | [x] Expected 1 space between comma and "'\r'"; 0 found
87 | ERROR | [x] Expected one space after the comma, 0 found
122 | ERROR | [x] Expected 1 space between comma and "'\r'"; 0 found
122 | ERROR | [x] Expected one space after the comma, 0 found
159 | ERROR | [ ] Protected method name
| | "AddToCalendarDisplayTest::getUTCEquivalentOfUserNowAsTimestamp"
| | is not in lowerCamel format
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PHPCBF CAN FIX THE 9 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: ...vb/d_cont/add_to_calendar/src/Plugin/Field/FieldType/AddToCalendarItem.php
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FOUND 1 ERROR AFFECTING 1 LINE
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10 | ERROR | [x] There must be one blank line after the last USE statement; 2
| | found;
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PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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Time: 267ms; Memory: 12MB

Steps to Reproduce

Execute the command: phpcs --standard=Drupal,DrupalPractice --extensions=php,module,inc,install,test,profile,theme,css,info,txt,md,yml,twig add_to_calendar/

Remaining tasks