Add support for annotation for turning off replaceable check

[Per Östlund]

#4646 was solved by introducing the --ignoreReplaceable flag for turning off the check that an element is replaceable before redeclaring it. Using this flag can mask actual mistakes by the user, so it would be good to have a more finegrained solution that allows the check to be turned off for an individual modifier. For example:

model M
  A a(redeclare model B = C annotation(__OpenModelica_IgnoreReplaceable));
end M;