🔧 MAINTAIN: Add pylint_aiida plugin

As discussed in #5176,
pylint does not understand the `@classproperty` decorator,
and so mistakes the method as a function, rather than an attribute of the class.
This commit adds a pylint transform plugin, to remove false-positives.
(see: https://pylint.pycqa.org/en/latest/how_tos/transform_plugins.html)

utils/pylint_aiida.py

@@ -0,0 +1,56 @@
+"""pylint plugin for ``aiida-core`` specific issues."""
+import astroid
+
+
+def register(linter):  # pylint: disable=unused-argument
+    """Register linters (unused)"""
+
+
+def remove_classprop_imports(import_from: astroid.ImportFrom):
+    """Remove any ``classproperty`` imports (handled in ``replace_classprops``)"""
+    import_from.names = [name for name in import_from.names if name[0] != 'classproperty']
+
+
+def replace_classprops(func: astroid.FunctionDef):
+    """Replace ``classproperty`` decorated methods.
+
+    As discussed in https://github.com/PyCQA/pylint/issues/1694, pylint does not understand the ``@classproperty``
+    decorator, and so mistakes the method as a function, rather than an attribute of the class.
+    If the method is annotated, this leads to pylint issuing ``no-member`` errors.
+
+    This transform replaces ``classproperty`` decorated methods with an annotated attribute::
+
+        from aiida.common.lang import classproperty
+
+        class MyClass:
+            @classproperty
+            def my_property(cls) -> AnnotatedType:
+                return cls.my_value
+
+        MyClass.my_property.attribute  # <-- pylint issues: Method 'my_property' has no 'attribute' member (no-member)
+
+        class MyClass:
+            my_property: AnnotatedType
+
+    """
+    # ignore methods without annotations or decorators
+    if not (func.returns and func.decorators and func.decorators.nodes):
+        return
+    # ignore methods that are specified as abstract
+    if any(isinstance(node, astroid.Name) and 'abstract' in node.name for node in func.decorators.nodes):
+        return
+    if any(isinstance(node, astroid.Attribute) and 'abstract' in node.attrname for node in func.decorators.nodes):
+        return
+    # convert methods with @classproperty decorator
+    if isinstance(func.decorators.nodes[0], astroid.Name) and func.decorators.nodes[0].name == 'classproperty':
+        assign = astroid.AnnAssign(lineno=func.lineno, col_offset=func.col_offset, parent=func.parent)
+        assign.simple = 1
+        assign.target = astroid.AssignName(func.name, lineno=assign.lineno, col_offset=assign.col_offset, parent=assign)
+        assign.annotation = func.returns
+        assign.annotation.parent = assign
+        func.parent.locals[func.name] = [assign.target]
+        return assign
+
+
+astroid.MANAGER.register_transform(astroid.ImportFrom, remove_classprop_imports)
+astroid.MANAGER.register_transform(astroid.FunctionDef, replace_classprops)