util: change GetWarnings parameter to bool
GetWarnings() changes the format of the output warning string based on a passed-in string argument that can be set to "gui" or "statusbar".
Change the argument to a bool:
- there are only two types of behaviour, so a bool is a more natural argument type
- changing the name to
verbosedoes not set any expectations for the how the calling code will use the returned string (currently,statusbaris used for RPC warnings, not a status bar) - removes some error-handling code for when the passed-in string is not one of the two strings expected.