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)
diff --git a/src/edit.c b/src/edit.c
index 65b760b..4071782 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -963,6 +963,7 @@
 	    break;
 
 	case K_BS:	// delete character before the cursor
+	case K_S_BS:
 	case Ctrl_H:
 	    did_backspace = ins_bs(c, BACKSPACE_CHAR, &inserted_space);
 	    auto_format(FALSE, TRUE);