Fix the issues reported by phpcs on block_extras module

Problem/Motivation

after executing phpcs command getting below errors.

 ./vendor/bin/phpcs   --standard="Drupal,DrupalPractice"   --extensions="php,module,inc,install,test,profile,theme,info" web/modules/contrib/block_extras/

FILE: /home/shivsharma/project/test/web/modules/contrib/block_extras/block_extras.module
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FOUND 1 ERROR AND 2 WARNINGS AFFECTING 3 LINES
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  9 | ERROR   | [x] Use statements should be sorted alphabetically. The first wrong one is Drupal\block_content\Entity\BlockContent.
 54 | WARNING | [x] A comma should follow the last multiline array item. Found: 'Block Extras'
 64 | WARNING | [x] A comma should follow the last multiline array item. Found: 'Block preview'
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PHPCBF CAN FIX THE 3 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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Time: 167ms; Memory: 10MB

Steps to reproduce

Execute:

 ./vendor/bin/phpcs   --standard="Drupal,DrupalPractice"   --extensions="php,module,inc,install,test,profile,theme,info" web/modules/contrib/block_extras/