Merge #17750: util: change GetWarnings parameter to bool

7aab8d1024 [style] Code style fixups in GetWarnings() (John Newbery)
492c6dc1e7 util: change GetWarnings parameter to bool (John Newbery)
869b6314fd [qt] remove unused parameter from getWarnings() (John Newbery)

Pull request description:

  `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 `verbose` does not set any expectations for the how the calling code will use the returned string (currently, `statusbar` is 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.

ACKs for top commit:
  laanwj:
    code review ACK 7aab8d1024
  practicalswift:
    ACK 7aab8d1024 -- diff looks correct :)
  MarcoFalke:
    ACK 7aab8d1024 otherwise.
  promag:
    Code review ACK 7aab8d1024.

Tree-SHA512: 75882c6e3e44aa9586411b803149b36ba487f4eb9cac3f5c8f07cd9f586870bba4488a51e674cf8147f05718534f482836e6a4e3f66e0d4ef6821900c7dfd04e

src/rpc/mining.cpp

@@ -254,7 +254,7 @@ static UniValue getmininginfo(const JSONRPCRequest& request)
     obj.pushKV("networkhashps",    getnetworkhashps(request));
     obj.pushKV("pooledtx",         (uint64_t)mempool.size());
     obj.pushKV("chain",            Params().NetworkIDString());
-    obj.pushKV("warnings",         GetWarnings("statusbar"));
+    obj.pushKV("warnings",         GetWarnings(false));
     return obj;
 }