[Settings> Save]: Shortcut key should be defined for 'Save' and 'Discard Changes' control inside Settings page.

### Windows Terminal version

1.12.3472.0

### Windows build number

10.0.22504.1010

### Other Software

**Test Environment:**
OS: Windows 11 Version Dev (OS Build 22504.1010)
App: Windows Terminal Preview
Screen Reader: Narrator
Tool: Accessibility Insights for Windows Version 1.1.1741.1

### Steps to reproduce

**Repro Steps:**
1. Open Windows Terminal.
2. Open Settings page using 'Ctr+,'.
3. Make some changes inside given tabs.
4. Verify that whether shortcuts is given to save or discard changes.

**User Experience:**
UX will not be good if Users like Keyboard only, Screen Reader users are not able Save or Discard changes fast.

**Attachments:**
[Shortcut key should be defined for 'Save' and 'Discard Changes' control inside Settings page..zip](https://github.com/microsoft/terminal/files/7773208/Shortcut.key.should.be.defined.for.Save.and.Discard.Changes.control.inside.Settings.page.zip)

### Expected Behavior

Shortcut keys should be defined for 'Save' and 'Discard Changes' control inside Settings page. Shortcut keys should also be included with 'Save' or Discard' button Accessible Name & Tooltip.
i.e. 'Ctrl+ S' to Save Changes and 'Ctrl + D' to Discard changes.

### Actual Behavior

Shortcut key is not defined for 'Save' and 'Discard Changes' control inside Settings page. Users have to navigate to Save or Discard button in order to save or discard changes.

Start by reproducing the Settings page behavior in Windows Terminal using the listed Windows and Terminal versions, then inspect the Settings page's Save and Discard Changes controls. Done means keyboard shortcuts are available for both controls and are included in their accessible names and tooltips, with the behavior verified using keyboard-only navigation and a screen reader.

Written by the indexing model from the issue text.