code refactor, php8.x adjustmentts, param types, etc

[jakwinkler]

Description (*)

Just some type fixes + upgrade to php8.x
Needs to be tested and validated properly, as some method properties still do not match in core.

I've made this fix due to this code:

   $items = $this->optionManagement->getItems(
         Product::ENTITY,
         $attributeCode
   );

as it suppose to be an integer, but string has to be passed as the $1 parameter

Contribution checklist (*)

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• README.md files for modified modules are updated and included in the pull request if any README.md predefined sections require an update
• All automated tests passed successfully (all builds are green)

Resolved issues:

1. resolves [Issue] code refactor, php8.x adjustmentts, param types, etc #39875: code refactor, php8.x adjustmentts, param types, etc

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[jakwinkler]

@magento run all tests

[jakwinkler]

@magento run all tests

[jakwinkler]

@magento run all tests

[engcom-Hotel]

@magento create issue

[ihor-sviziev]

@jakwinkler, I do agree with these changes in general, but they most likely will break anyone who extended from these interfaces or classes.
Usually it takes too much time for approve such changes, but we can wait