CLI: change "-suppress warnings" option to "-nowarn"

Following the rule of the least surprise: this option is named "-nowarn" in
other JVM language compilers. Besides, having an option with an argument which
can take exactly one predefined value is sort of confusing

compiler/testData/cli/jvm/wrongArgument.out

@@ -11,10 +11,10 @@ where possible options include:
   -module <path>             Path to the module file to compile
   -script                    Evaluate the script file
   -kotlin-home <path>        Path to Kotlin compiler home directory, used for annotations and runtime libraries discovery
+  -nowarn                    Generate no warnings
   -tags                      Demarcate each compilation message (error, warning, etc) with an open and close tag
   -verbose                   Enable verbose logging output
   -version                   Display compiler version
   -help (-h)                 Print a synopsis of standard options
-  -suppress warnings         Suppress all compiler warnings
   -X                         Print a synopsis of advanced options
 INTERNAL_ERROR