Merge bitcoin/bitcoin#26889: refactor: wallet, remove global 'ArgsManager' dependency

52f4d567d6 refactor: remove <util/system.h> include from wallet.h (furszy)
6c9b342c30 refactor: wallet, remove global 'ArgsManager' access (furszy)
d8f5fc4462 wallet: set '-walletnotify' script instead of access global args manager (furszy)
3477a28dd3 wallet: set keypool_size instead of access global args manager (furszy)

Pull request description:

  Structurally, the wallet class shouldn't access the global `ArgsManager` class, its internal behavior shouldn't be coupled to a global command line args parsing object.

  So this PR migrates the only two places where we depend on it: (1) the keypool size, and (2) the "-walletnotify" script. And cleans up the, now unneeded, wallet `ArgsManager` ref member.

  Extra note:
  In the process of removing the args ref member, discovered and fixed files that were invalidly depending on the wallet header including `util/system.h`.

ACKs for top commit:
  achow101:
    ACK 52f4d567d6
  TheCharlatan:
    Re-ACK 52f4d567d6
  hebasto:
    re-ACK 52f4d567d6

Tree-SHA512: 0cffd99b4dd4864bf618aa45aeaabbef2b6441d27b6dbb03489c4e013330877682ff17b418d07aa25fbe1040bdf2c67d7559bdeb84128c5437bf0e6247719016

src/qt/optionsmodel.cpp

@@ -18,6 +18,7 @@
 #include <netbase.h>
 #include <txdb.h>       // for -dbcache defaults
 #include <util/string.h>
+#include <util/system.h>
 #include <validation.h> // For DEFAULT_SCRIPTCHECK_THREADS
 #include <wallet/wallet.h> // For DEFAULT_SPEND_ZEROCONF_CHANGE
 
@@ -668,6 +669,11 @@ bool OptionsModel::isRestartRequired() const
     return settings.value("fRestartRequired", false).toBool();
 }
 
+bool OptionsModel::hasSigner()
+{
+    return gArgs.GetArg("-signer", "") != "";
+}
+
 void OptionsModel::checkAndMigrate()
 {
     // Migration of default values