Fix the issues reported by phpcs

Problem/Motivation

FILE: /var/www/html/web/modules/custom/ief_popup/ief_popup.module
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FOUND 7 ERRORS AND 1 WARNING AFFECTING 6 LINES
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  43 | ERROR   | [ ] unserialize() is insecure unless allowed classes are limited. Use a safe format like JSON or use the allowed_classes option.
  94 | WARNING | [ ] Line exceeds 80 characters; contains 86 characters
  98 | ERROR   | [x] TRUE, FALSE and NULL must be uppercase; expected "FALSE" but found "false"
 119 | ERROR   | [ ] All functions defined in a module file must be prefixed with the module's name, found "_process_ief_form" but expected "ief_popup__process_ief_form"
 119 | ERROR   | [ ] Type hint "array" missing for $ief_form
 119 | ERROR   | [ ] Type hint "array" missing for $parameters
 215 | ERROR   | [x] Short array syntax must be used to define arrays
 229 | ERROR   | [ ] All functions defined in a module file must be prefixed with the module's name, found "_ief_form_after_build" but expected "ief_popup__ief_form_after_build"
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PHPCBF CAN FIX THE 2 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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FILE: /var/www/html/web/modules/custom/ief_popup/ief_popup.libraries.yml
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FOUND 1 ERROR AFFECTING 1 LINE
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 12 | ERROR | [x] Expected 1 newline at end of file; 0 found
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PHPCBF CAN FIX THE 1 MARKED SNIFF VIOLATIONS AUTOMATICALLY
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Steps to reproduce

Run the command phpcs --standard="DrupalPractice,Drupal" ief_popup

Proposed resolution

Resolve coding standard issue and create the patch.

Remaining tasks

User interface changes

API changes

Data model changes