patch 8.2.4876: MS-Windows: Shift-BS results in strange char in powershell

Problem:    MS-Windows: Shift-BS results in strange character in powershell.
Solution:   Add K_S_BS. (Christian Brabandt, closes #10283, closes #10279)

src/testdir/test_edit.vim

@@ -2148,5 +2148,31 @@ func Test_edit_overlong_file_name()
   bwipe!
 endfunc
 
+func Test_edit_shift_bs()
+  CheckMSWindows
+
+  " FIXME: this works interactively, but the test fails
+  throw 'Skipped: Shift-Backspace Test not working correctly :('
+
+  " Need to run this in Win32 Terminal, do not use CheckRunVimInTerminal
+  if !has("terminal")
+    return
+  endif
+
+  " Shift Backspace should work like Backspace in insert mode
+  let lines =<< trim END
+    call setline(1, ['abc'])
+  END
+  call writefile(lines, 'Xtest_edit_shift_bs')
+
+  let buf = RunVimInTerminal('-S Xtest_edit_shift_bs', #{rows: 3})
+  call term_sendkeys(buf, "A\<S-BS>-\<esc>")
+  call TermWait(buf, 50)
+  call assert_equal('ab-', term_getline(buf, 1))
+
+  " clean up
+  call StopVimInTerminal(buf)
+  call delete('Xtest_edit_shift_bs')
+endfunc
 
 " vim: shiftwidth=2 sts=2 expandtab