PasswordDialog: merge components and bug fixes

This commit merges PasswordDialog, PassphraseDialog and
NewPasswordDialog. Also the following bugs were fixed:

- Wizard pages still being active when opening a wallet
  from wizard.
- Capslock detection was buggy when copy pasting password, I
  replaced it with native implementations for each platform.
- isAlpha could throw errors when using special characters.

pages/settings/SettingsWallet.qml

@@ -339,7 +339,7 @@ Rectangle {
                 onClicked: {
                     passwordDialog.onAcceptedCallback = function() {
 	                    if(appWindow.walletPassword === passwordDialog.password){
-	                        newPasswordDialog.open()
+	                        passwordDialog.openNewPasswordDialog()
 	                    } else {
 	                        informationPopup.title  = qsTr("Error") + translationManager.emptyString;
                             informationPopup.text = qsTr("Wrong password") + translationManager.emptyString;