Fix #12280: Analysis depends on order of union type

[phpstan-bot]

Summary

When accessing a property on a union type where the members have different visibilities (e.g., A|B where A::$date is public and B::$date is private), PHPStan incorrectly reported "Access to protected property" depending on the order of types in the union.

Changes

• Added getProperties() getter to src/Reflection/Type/UnionTypePropertyReflection.php to expose inner property reflections
• Modified canReadProperty() and canWriteProperty() in src/Analyser/MutatingScope.php to check each inner property's accessibility individually when given a UnionTypePropertyReflection
• Added regression test in tests/PHPStan/Rules/Properties/data/bug-12280.php and tests/PHPStan/Rules/Properties/AccessPropertiesRuleTest.php

Root cause

UnionTypePropertyReflection::isPublic() uses AND semantics across all inner properties — it returns true only if ALL inner properties are public. Similarly for isPrivate(). When one property is public and another is private, both return false, causing canAccessClassMember() to fall through to the "protected" branch.

Additionally, getDeclaringClass() returns only the first property's declaring class, making the protected-access check order-dependent: with A|self, A's declaring class was checked (not related to current class B → error); with self|A, B's declaring class was checked (matches current scope → no error).

The fix checks each inner property individually through canReadProperty/canWriteProperty, which correctly handles mixed visibilities — A::$date passes as public, and B::$date passes as accessible from within B's scope.

Test

Added tests/PHPStan/Rules/Properties/data/bug-12280.php with two test methods: test1 uses A|self order and test2 uses self|A order, both accessing a property where A::$date is public and B::$date is private from within B's static method. Both should produce no errors.

Fixes phpstan/phpstan#12280