[Hosts] Backup Settings (#37778)

<!-- 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)?
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## Summary of the Pull Request

Add backup settings for the Hosts File Editor to allow users to
customize the existing hardcoded logic.

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## PR Checklist

- [x] **Closes:** #37666
- [ ] **Communication:** I've discussed this with core contributors
already. If work hasn't been agreed, this work might be rejected
- [x] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end user facing strings can be localized
- [ ] **Dev docs:** Added/updated
- [ ] **New binaries:** Added on the required places
- [ ] [JSON for
signing](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ESRPSigning_core.json)
for new binaries
- [ ] [WXS for
installer](https://github.com/microsoft/PowerToys/blob/main/installer/PowerToysSetup/Product.wxs)
for new binaries and localization folder
- [ ] [YML for CI
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/ci/templates/build-powertoys-steps.yml)
for new test projects
- [ ] [YML for signed
pipeline](https://github.com/microsoft/PowerToys/blob/main/.pipelines/release.yml)
- [x] **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:
https://github.com/MicrosoftDocs/windows-dev-docs/pull/5342

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or any additional comments/features here -->
## Detailed Description of the Pull Request / Additional comments

<img width="707" alt="image"
src="https://github.com/user-attachments/assets/e114431e-60e0-4b8c-bba7-df23f7af0182"
/>

<img width="707" alt="image"
src="https://github.com/user-attachments/assets/a02b591e-eb46-4964-bee7-548ec175b3aa"
/>

<img width="707" alt="image"
src="https://github.com/user-attachments/assets/6eb0ff21-74fa-4229-8832-df2df877b5cd"
/>

<!-- Describe how you validated the behavior. Add automated tests
wherever possible, but list manual validation steps taken as well -->
## Validation Steps Performed

- Backup on: verified that backup isn't executed
- Backups off: Verified that only one backup is executed
- Verified that backup is located in the expected path
- Auto delete is set to "never": verified that no backups are deleted
- Auto delete is set to "based on count": verified that backups are
deleted according to count value
- Auto delete is set to "based on age and count": verified that backups
are deleted according to days and count values
- Verified that files without the backup pattern aren't deleted
- There is also adequate test coverage for these scenarios 🚀

---------

Co-authored-by: Gordon Lam (SH) <yeelam@microsoft.com>

src/settings-ui/Settings.UI/Strings/en-us/Resources.resw

@@ -5599,4 +5599,48 @@ To record a specific window, enter the hotkey with the Alt key in the opposite m
   <data name="Shortcut_Conflict_LearnMore.Content" xml:space="preserve">
     <value>Learn more</value>
   </data>
+  <data name="Hosts_Backup_GroupSettings.Header" xml:space="preserve">
+    <value>Backup</value>
+  </data>
+  <data name="Hosts_Backup.Header" xml:space="preserve">
+    <value>Backup hosts file</value>
+    <comment>"Hosts" refers to the system hosts file, do not loc</comment>
+  </data>
+  <data name="Hosts_Backup.Description" xml:space="preserve">
+    <value>Automatically create a backup of the hosts file when you save for the first time in a session</value>
+    <comment>"Hosts" refers to the system hosts file, do not loc</comment>
+  </data>
+  <data name="Hosts_Backup_Location.Header" xml:space="preserve">
+    <value>Location</value>
+  </data>
+  <data name="Hosts_ButtonSelectLocation.Text" xml:space="preserve">
+    <value>Select location</value>
+  </data>
+  <data name="Hosts_Delete_Backup.Header" xml:space="preserve">
+    <value>Automatically delete backups</value>
+  </data>
+  <data name="Hosts_Backup_DaysInput.Header" xml:space="preserve">
+    <value>Days</value>
+  </data>
+  <data name="Hosts_Backup_CountInput_Description" xml:space="preserve">
+    <value>Set the number of backups to keep. Older backups will be deleted once the limit is reached.</value>
+  </data>
+  <data name="Hosts_Backup_DaysInput.Description" xml:space="preserve">
+    <value>Set the number of days to keep backups. Older backups will be deleted once the limit is reached.</value>
+  </data>
+  <data name="Hosts_DeleteBackupMode_Never.Content" xml:space="preserve">
+    <value>Never</value>
+  </data>
+  <data name="Hosts_DeleteBackupMode_CountBased.Content" xml:space="preserve">
+    <value>Based on count</value>
+  </data>
+  <data name="Hosts_DeleteBackupMode_AgeAndCountBased.Content" xml:space="preserve">
+    <value>Based on age and count</value>
+  </data>
+  <data name="Hosts_Backup_CountInput_Age_Description" xml:space="preserve">
+    <value>Set an optional number of backups to always keep despite their age</value>
+  </data>
+  <data name="Hosts_Backup_CountInput_Header" xml:space="preserve">
+    <value>Backup count</value>
+  </data>
 </root>