[ondrejmirtes]

Rewrites part of src/Rules/Api on top of the restricted usage extension framework, and adds tip support to RestrictedUsage, which the BC-promise rules need.

Commits

1. Allow restricted usage extensions to return a tip. RestrictedUsage::create() takes an optional ?string $tip. This is backward compatible for the @api class. All 12 places that turn a RestrictedUsage into a rule error now attach the tip: the 10 Restricted*UsageRule classes, ClassNameCheck, and the constructor check in InstantiationRule.
2. Rewrite the runtime reflection Api rules as restricted usage extensions.
   • RuntimeReflectionFunctionRule → RuntimeReflectionFunctionUsageExtension (function usage)
   • RuntimeReflectionInstantiationRule → RuntimeReflectionInstantiationUsageExtension (class name usage at the new location)
3. Rewrite the Api extends / implements / trait-use rules as one restricted class name usage extension. ApiClassExtendsRule, ApiClassImplementsRule, ApiInterfaceExtendsRule and ApiTraitUseRule → ApiClassNameUsageExtension, which switches on ClassNameUsageLocation.

Messages, identifiers, tips and lines are unchanged. The tests now run through the host rules (ExistingClassInClassExtendsRule, InstantiationRule, …), so they also expect the host rules' own errors on the existing data, e.g. "extends final class FileTypeMapper".

Small behaviour differences

• is_a(...) and similar first-class callables are now reported too, through RestrictedFunctionCallableUsageRule.
• new parent() that resolves to a Reflection* class is not reported any more. Host rules don't pass self, static or parent to class-name extensions.
• Errors for multi-line class declarations are reported on the line of the referenced name, not on the line where the class starts.

Still rules, and why

Rule	Missing in the framework
ApiMethodCallRule, ApiStaticCallRule, ApiInstantiationRule	RestrictedMethodUsageExtension has no usage location. One extension is called for ->m(), ::m(), first-class callables and the constructor on new X, but these rules treat __construct differently. ApiInstantiationRule also can't use class-name usage: InstantiationRule skips self/static/parent and drops class-name errors when it returns early for abstract classes, interfaces, traits or enums.
ApiClassConstFetchRule	The CLASS_CONSTANT_ACCESS location carries no constant name when the constant doesn't exist or is ::class.
ApiInstanceofRule, ApiInstanceofTypeRule	Extensions get no AST node: the instanceof expression type, the TypeTraverserInstanceofVisitor attribute, and the class name as written in the source are all unavailable.
GetTemplateTypeRule, NodeConnectingVisitorAttributesRule	Method usage extensions get no call arguments.
PhpStanNamespaceIn3rdPartyPackageRule, OldPhpParser4ClassRule	There is no extension point for namespace declarations or for class names that don't exist.