fix(phpstan): improved method validity checks and reduced error handling

This commit fixes several issues in different PHP files.

• Added method_exists checks for isActive method in activate.php, deactivate.php and toggle.php to prevent calls to an undefined method.
• Similar check added for getTitle method in get.php.
• Fixed sorting functionality in search.php by using strcmp instead of greater than comparison.
• Removed a large number of ignored errors in phpstan-baseline.neon, indicating reduced error handling.
• Corrected the implode parameters order in Discount.php and typecasted variable to string before using explode in PriceFactor.php.
• Updated getTitle & toPriceFactor method parameters in Discount.php to use union types for compatibility with different data types.

Related: #18 (closed)

.phive/phars.xml

 <?xml version="1.0" encoding="UTF-8"?>
 <phive xmlns="https://phar.io/phive">
-  <phar name="phpstan" version="^1.10.67" installed="1.10.67" location="./tools/phpstan" copy="false"/>
+  <phar name="phpstan" version="1.11.8" installed="1.11.8" location="./tools/phpstan" copy="false"/>
+  <phar name="phpunit" version="^10.5.20" installed="10.5.20" location="./tools/phpunit" copy="false"/>
+  <phar name="phpcs" version="^3.10.1" installed="3.10.1" location="./tools/phpcs" copy="false"/>
+  <phar name="phpcbf" version="^3.10.1" installed="3.10.1" location="./tools/phpcbf" copy="false"/>
+  <phar name="captainhook" version="^5.23.3" installed="5.23.3" location="./tools/captainhook" copy="false"/>
 </phive>