Moved SettingVisibilityPreset loading to it's own class

Since there was so much debate regarding the unit testing of the visiblity presets, i had another look at it.
The old version was almost untestable because all functionalities were mushed together into a single class.

CURA-5734

cura/Settings/SettingVisibilityPreset.py

@@ -0,0 +1,87 @@
+import os
+import urllib.parse
+from configparser import ConfigParser
+from typing import List
+
+from PyQt5.QtCore import pyqtProperty, QObject, pyqtSignal
+
+from UM.Logger import Logger
+from UM.MimeTypeDatabase import MimeTypeDatabase, MimeTypeNotFoundError
+
+
+class SettingVisibilityPreset(QObject):
+    onSettingsChanged = pyqtSignal()
+    onNameChanged = pyqtSignal()
+    onWeightChanged = pyqtSignal()
+    onIdChanged = pyqtSignal()
+
+    def __init__(self, id: str = "", name: str = "" , weight: int = 0, parent = None) -> None:
+        super().__init__(parent)
+        self._settings = []  # type: List[str]
+        self._id = id
+        self._weight = weight
+        self._name = name
+
+    @pyqtProperty("QStringList", notify = onSettingsChanged)
+    def settings(self) -> List[str]:
+        return self._settings
+
+    @pyqtProperty(str, notify=onIdChanged)
+    def id(self) -> str:
+        return self._id
+
+    @pyqtProperty(int, notify=onWeightChanged)
+    def weight(self) -> int:
+        return self._weight
+
+    @pyqtProperty(str, notify=onNameChanged)
+    def name(self) -> str:
+        return self._name
+
+    def setName(self, name: str) -> None:
+        if name != self._name:
+            self._name = name
+            self.onNameChanged.emit()
+
+    def setId(self, id: int) -> None:
+        if id != self._id:
+            self._id = id
+            self.onIdChanged.emit()
+
+    def setWeight(self, weight: str) -> None:
+        if weight != self._weight:
+            self._weight = weight
+            self.onWeightChanged.emit()
+
+    def setSettings(self, settings: List[str]) -> None:
+        if settings != self._settings:
+            self._settings = settings
+            self.onSettingsChanged.emit()
+
+    def loadFromFile(self, file_path: str) -> None:
+        mime_type = MimeTypeDatabase.getMimeTypeForFile(file_path)
+
+        item_id = urllib.parse.unquote_plus(mime_type.stripExtension(os.path.basename(file_path)))
+        if not os.path.isfile(file_path):
+            Logger.log("e", "[%s] is not a file", file_path)
+            return None
+
+        parser = ConfigParser(allow_no_value=True)  # Accept options without any value,
+
+        parser.read([file_path])
+        if not parser.has_option("general", "name") or not parser.has_option("general", "weight"):
+            return None
+
+        settings = []  # type: List[str]
+        for section in parser.sections():
+            if section == "general":
+                continue
+
+            settings.append(section)
+            for option in parser[section].keys():
+                settings.append(option)
+        self.setSettings(settings)
+        self.setId(item_id)
+        self.setName(parser["general"]["name"])
+        self.setWeight(parser["general"]["weight"])
+