[13.x] Fix null deprecation warnings in additional validation rules

[niduranga]

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PR Description (Copy & Paste meka)

Description
Fixes the null deprecation warnings in AnyOf, ArrayRule, and Can validation rules. These rules followed an identical pattern to the issues previously fixed in Contains, DoesntContain, In, and NotIn rules (#59561), where passing a null value to internal string functions triggered deprecation warnings in PHP 8.1+.

Example

// AnyOf, ArrayRule, or Can with null values
Rule::anyOf([1, null, 'active']);
// Before: Deprecated warning (null cast to string)
// After: No warning (null cast to empty string)

Rule	Fixed	Reference
Contains	✅	#59561
DoesntContain	✅	#59561
In	✅	#59576
NotIn	✅	#59576
AnyOf	✅	This PR
ArrayRule	✅	This PR
Can	✅	This PR

Changes

• src/Illuminate/Validation/Rules/AnyOf.php - Cast value to string
• src/Illuminate/Validation/Rules/ArrayRule.php - Cast enum values to string
• src/Illuminate/Validation/Rules/Can.php - Cast value to string for Gate

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