Disable Style/AccessModifierDeclarations for all files

This cop was only introduced relatively recently and it seems to have
stirred up some controversy [1].

It was being triggered in many of the acceptance tests where anonymous
classes are defined within a test and their methods' visibility is
specified "inline".

[1]: rubocop/rubocop#5953

.rubocop.yml

@@ -50,3 +50,7 @@ Style/WhileUntilModifier:
 # frozen_string_literal magic comment has only been supported since Ruby v2.3
 Style/FrozenStringLiteralComment:
   Enabled: false
+
+# This recently introduced cop seems to have stirred up some controversy
+Style/AccessModifierDeclarations:
+  Enabled: false

.rubocop_todo.yml

@@ -83,12 +83,6 @@ Metrics/ModuleLength:
 Metrics/PerceivedComplexity:
   Max: 11
 
-# Offense count: 97
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: inline, group
-Style/AccessModifierDeclarations:
-  Enabled: false
-
 # Offense count: 105
 Style/Documentation:
   Enabled: false