fix: Update key shortcut for backindentline to Shift+Tab

- Changed the default key binding for "backindentline" from "Shift+Backtab" to "Shift+Tab" in settings.json and settings.json.in for consistency and improved user experience.

bug: https://pms.uniontech.com/bug-view-345247.html

Author: dengzhongyuan365-dev

src/resources/settings.json

@@ -255,7 +255,7 @@
                             "key": "backindentline",
                             "name": "Decrease indent",
                             "type": "keySequenceEdit",
-                            "default":  "Shift+Backtab"
+                            "default":  "Shift+Tab"
                         },
                         {
                             "key": "forwardchar",
@@ -726,7 +726,7 @@
                             "key": "backindentline",
                             "hide" : true,
                             "reset" : false,
-                            "default":  "Shift+Backtab"
+                            "default":  "Shift+Tab"
                         },
                         {
                             "key": "forwardchar",

src/resources/settings.json.in

@@ -255,7 +255,7 @@
                             "key": "backindentline",
                             "name": "Decrease indent",
                             "type": "keySequenceEdit",
-                            "default":  "Shift+Backtab"
+                            "default":  "Shift+Tab"
                         },
                         {
                             "key": "forwardchar",
@@ -726,7 +726,7 @@
                             "key": "backindentline",
                             "hide" : true,
                             "reset" : false,
-                            "default":  "Shift+Backtab"
+                            "default":  "Shift+Tab"
                         },
                         {
                             "key": "forwardchar",