refactor: Add simple clang-tidy readability checks (#6556)

This change enables the following clang-tidy checks:
-  readability-avoid-nested-conditional-operator,
-  readability-avoid-return-with-void-value,
-  readability-braces-around-statements,
-  readability-const-return-type,
-  readability-container-contains,
-  readability-container-size-empty,
-  readability-else-after-return,
-  readability-make-member-function-const,
-  readability-redundant-casting,
-  readability-redundant-inline-specifier,
-  readability-redundant-member-init,
-  readability-redundant-string-init,
-  readability-reference-to-constructed-temporary,
-  readability-static-definition

src/test/app/Ticket_test.cpp

@@ -286,11 +286,15 @@ class Ticket_test : public beast::unit_test::suite
 
                     BEAST_EXPECT(prevTicketCount > 0);
                     if (prevTicketCount == 1)
+                    {
                         BEAST_EXPECT(!finalFields.isMember(sfTicketCount.jsonName));
+                    }
                     else
+                    {
                         BEAST_EXPECT(
                             finalFields.isMember(sfTicketCount.jsonName) &&
                             finalFields[sfTicketCount.jsonName].asUInt() == prevTicketCount - 1);
+                    }
                 }
             }
             else if (node.isMember(sfDeletedNode.jsonName))