refactor: DoubleValidationDelegate moved to qt_utils

bec_widgets/qt_utils/__init__.py

@@ -1,2 +1,3 @@
 from .crosshair import Crosshair
 from .colors import Colors
+from .validator_delegate import DoubleValidationDelegate

bec_widgets/qt_utils/validator_delegate.py

@@ -0,0 +1,10 @@
+from PyQt5.QtGui import QDoubleValidator
+from PyQt5.QtWidgets import QStyledItemDelegate, QLineEdit
+
+
+class DoubleValidationDelegate(QStyledItemDelegate):
+    def createEditor(self, parent, option, index):
+        editor = QLineEdit(parent)
+        validator = QDoubleValidator()
+        editor.setValidator(validator)
+        return editor