PY-32472, PY-36767: Ignore Django CBV methods' params that are required by signature + fix NPE

request, *args and **kwargs should not be marked as "unused" in CBV.

"request" is part of signature and args are used to pass "as-is" to the dispatch

GitOrigin-RevId: c83d7301252e7982254a7aadbe33ed07fa7accec

python/src/com/jetbrains/extensions/python/PyFunctionExt.kt

@@ -0,0 +1,22 @@
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+package com.jetbrains.extensions.python
+
+import com.jetbrains.python.FunctionParameter
+import com.jetbrains.python.psi.PyFunction
+import com.jetbrains.python.psi.PyParameter
+
+fun PyFunction.getParameter(paramToSearch: FunctionParameter): PyParameter? {
+  val parameterList = this.parameterList
+  val position = paramToSearch.position
+  val name = paramToSearch.name
+  if (name != null) {
+    parameterList.findParameterByName(name)?.let {
+      return it
+    }
+  }
+  if (position != FunctionParameter.POSITION_NOT_SUPPORTED) {
+    val hasSelf = containingClass != null
+    return parameterList.parameters.getOrNull(if (hasSelf) position + 1 else position)
+  }
+  return null
+}