Php 8.2 Deprecation Warning Fixes

[anktd]

Recently a bug was reported about deprecated warning on installing the Blockonomics plugin -> Ticket here.

Fix: Changed the parent slug in add_submenu_page() from empty string to 'options.php' to resolve PHP 8.1 deprecation warnings while maintaining hidden menu functionality ➞ f7784a3

• Before this, we were using null:
  • Using it caused PHP 8.1 deprecation warnings in WordPress core functions
  • Specifically triggers warnings in:
    • strpos(): When WordPress checks menu hierarchy
    • str_replace(): During menu slug processing
  • This occurs because WordPress core functions expect string types but receive null
• Using empty string ('') (as the suggested fix by user report):
  • Resolves the initial strpos/str_replace warnings
  • However, triggers new deprecation warning in strip_tags()
  • This happens because WordPress internally converts empty string to null during menu processing
  • The conversion occurs before the string reaches admin-header.php
• Using 'options.php':
  • References WordPress core options handling system
  • Maintains proper string type throughout WordPress menu processing
  • Prevents type coercion issues that lead to deprecation warnings
  • Standard WordPress pattern for hidden admin pages
  • Doesn't create visible menu items while ensuring proper page registration

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Other fixes in this PR:

• Remove incorrect wpdb::prepare usage in uninstall hook by removing unnecessary prepare call for static queries ➞ 20fa454

• Added explicit property declaration private $api_key; to the Blockonomics_Setup class to comply with PHP 8.2's deprecation of dynamic properties ➞ 573320a

[anktd]

Tested changes working with Php 8.2.0, 8.1.13 and 7.4.33 ✅

[ashthecoder05]

Looks good! Added some clarifying questions for my understanding 🎖️