[Light Switch] Hotfixes (#42434)

<!-- Enter a brief description/summary of your PR here. What does it
fix/what does it change/how was it tested (even manually, if necessary)?
-->
## Summary of the Pull Request
Adds new "Off" mode for the schedule mode options which disable the
schedule.
Adds explicit function to disable light switch by default.

<!-- Please review the items on the PR checklist before submitting-->
## PR Checklist

Closes: 
- #42402 
New behavior: "Off" mode added. when off, the regular service loop stops
and all actions are event driven to either resume the loop or listen for
hotkey.
- #42386
New behavior: Disabled explicitly by default
- #42389
New behavior: When switching from dark to light mode the system theme
will remove the accent color.
- #42513
New behavior: Manual mode no longer gets reset. It was being overridden
by the sun calculations that were invertedly running when in manual
mode.

Todo:
- [ ] **Documentation updated:** If checked, please file a pull request
on [our docs
repo](https://github.com/MicrosoftDocs/windows-uwp/tree/docs/hub/powertoys)
and link it here: #xxx @alvinashcraft we will need to add this new mode
to the documentation.

## Validation Steps Performed
- Removed all default settings and tested new logic. Light Switch is set
to off by default.
- Updated UI and tested new "Off" mode, logs indicate mode switched and
ticker stopped. Polling resumes on mode change. (need to check that the
shortcut still works)

---------

Co-authored-by: Niels Laute <niels.laute@live.nl>
Co-authored-by: Gordon Lam <73506701+yeelam-gordon@users.noreply.github.com>

src/settings-ui/Settings.UI/Converters/EnumToVisibilityConverter.cs

@@ -1,37 +0,0 @@
-// Copyright (c) Microsoft Corporation
-// The Microsoft Corporation licenses this file to you under the MIT license.
-// See the LICENSE file in the project root for more information.
-
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
-using Microsoft.UI.Xaml;
-using Microsoft.UI.Xaml.Data;
-
-namespace Microsoft.PowerToys.Settings.UI.Converters
-{
-    public partial class EnumToVisibilityConverter : IValueConverter
-    {
-        public object Convert(object value, Type targetType, object parameter, string language)
-        {
-            if (value == null || parameter == null)
-            {
-                return Visibility.Collapsed;
-            }
-
-            string enumString = value.ToString();
-            string targetString = parameter.ToString();
-
-            return enumString.Equals(targetString, StringComparison.OrdinalIgnoreCase)
-                ? Visibility.Visible
-                : Visibility.Collapsed;
-        }
-
-        public object ConvertBack(object value, Type targetType, object parameter, string language)
-        {
-            throw new NotImplementedException();
-        }
-    }
-}