add ability to disable error using "@scala.annotation.nowarn" instead of "@SuppressWarnings"

[eranmizrahi1]

• Scala version: 2.13.11
• wartremover version: 3.1.5

steps:

define a case class without "final" keyword:

case class Foo(a: Int, b: String)

try to ignore the error using "@scala.annotation.nowarn" fails:

@scala.annotation.nowarn
case class Foo(a: Int, b: String)