[CodeQuality] Deprecate TypeNullableEntityFromDocblockRector

[TomasVotruba]

TypeNullableEntityFromDocblockRector is the only non-deprecated rule not part of any set. It is too opinionated and narrow use-cased to belong in a general code-quality set: it blindly forces all entity properties to nullable native types read from docblocks — a niche stepping-stone, not a broadly safe cleanup.

Deprecating it (joins the 4 already-deprecated orphan rules in CodeQuality/Rector/Class_).

Change

• Rule now implements DeprecatedInterface + @deprecated docblock
• Test suite removed (matches convention of the other deprecated rules)

-final class TypeNullableEntityFromDocblockRector extends AbstractRector
+/**
+ * @deprecated as too opinionated and narrow use-cased ...
+ */
+final class TypeNullableEntityFromDocblockRector extends AbstractRector implements DeprecatedInterface