Hosts: add “No leading spaces” option and honor it when saving (#41206)

## Summary of the Pull Request

Adds a new Hosts File Editor setting “No leading spaces” that prevents
prepending spaces to active lines when saving the hosts file (when any
entry is disabled). Default is Off to preserve current behavior.



## PR Checklist

- [x] Closes: #36386  

- [ ] Communication: N/A (small, scoped option)

- [x] Tests: Added/updated and all pass

- [x] Localization: New en-US strings added; other locales handled by
loc pipeline

- [ ] Dev docs: N/A

- [x] New binaries: None

- [x] Documentation updated: N/A



## Detailed Description of the Pull Request / Additional comments

- Settings surface:

  - `src/settings-ui/Settings.UI.Library/HostsProperties.cs`: add
`NoLeadingSpaces`

  - `src/modules/Hosts/HostsUILib/Settings/IUserSettings.cs`: add
`NoLeadingSpaces`

  - `src/modules/Hosts/Hosts/Settings/UserSettings.cs`: load/save value
from settings.json

  - `src/settings-ui/Settings.UI/ViewModels/HostsViewModel.cs`: expose
`NoLeadingSpaces`

  - `src/settings-ui/Settings.UI/SettingsXAML/Views/HostsPage.xaml`: new
SettingsCard toggle

  - `src/settings-ui/Settings.UI/Strings/en-us/Resources.resw`: add
`Hosts_NoLeadingSpaces.Header/Description`

- Writer change:

  - `src/modules/Hosts/HostsUILib/Helpers/HostsService.cs`: gate indent
with `anyDisabled && !_userSettings.NoLeadingSpaces`

- Tests:

  - `src/modules/Hosts/Hosts.Tests/HostsServiceTest.cs`:
`NoLeadingSpaces_Disabled_RemovesIndent`



Backward compatibility: default Off, current formatting unchanged unless
the user enables the option.



## Validation Steps Performed

- Automated: `HostsEditor.UnitTests` including
`NoLeadingSpaces_Disabled_RemovesIndent` passing.

- Manual:

  1. Run PowerToys (runner) as Admin.

  2. Settings → Hosts File Editor → enable “No leading spaces”.

  3. In editor, add active `127.0.0.10 example1` and disabled
`127.0.0.11 example2`; Save.

  4. Open `C:\Windows\System32\drivers\etc\hosts` in Notepad.

     - ON: active line starts at column 0; disabled is `# 127...`.

     - OFF: active line begins with two spaces when a disabled entry
exists.

src/settings-ui/Settings.UI/ViewModels/HostsViewModel.cs

@@ -105,6 +105,19 @@ namespace Microsoft.PowerToys.Settings.UI.ViewModels
             }
         }
 
+        public bool NoLeadingSpaces
+        {
+            get => Settings.Properties.NoLeadingSpaces;
+            set
+            {
+                if (value != Settings.Properties.NoLeadingSpaces)
+                {
+                    Settings.Properties.NoLeadingSpaces = value;
+                    NotifyPropertyChanged();
+                }
+            }
+        }
+
         public int AdditionalLinesPosition
         {
             get => (int)Settings.Properties.AdditionalLinesPosition;