fix(VTreeview): indent lines should support RTL

fixes #21952

Author: J-Sek

packages/vuetify/src/components/VTreeview/VTreeviewItem.sass

@@ -37,10 +37,10 @@
 
   .v-treeview-indent-lines
     position: absolute
-    left: 0
+    inset-inline-start: 0
     height: 100%
     display: grid
-    padding-left: $treeview-indent-lines-padding-left
+    padding-inline-start: $treeview-indent-lines-padding-left
     padding-block: $treeview-indent-lines-gap
     grid-template-columns: repeat(var(--v-indent-parts, 1), var(--prepend-width))
     opacity: $treeview-indent-lines-opacity
@@ -53,7 +53,7 @@
 
     &--leaf,
     &--line
-      border-left-width: $treeview-indent-line-width
+      border-inline-start-width: $treeview-indent-line-width
       height: 100%
       width: calc(50% + #{$treeview-indent-line-width-half})
       justify-self: end
@@ -74,18 +74,22 @@
     &--leaf-link
       border-bottom-width: $treeview-indent-line-width
       height: calc(50% + #{$treeview-indent-line-width-half})
-      margin-left: $treeview-indent-lines-gap
-      margin-right: $treeview-indent-line-leaf-link-margin-right
+      margin-inline-start: $treeview-indent-lines-gap
+      margin-inline-end: $treeview-indent-line-leaf-link-margin-right
 
     &--last-leaf
-      border-left-width: $treeview-indent-line-width
+      border-inline-start-width: $treeview-indent-line-width
       border-bottom-width: $treeview-indent-line-width
       height: calc(50% + #{$treeview-indent-line-width-half})
-      margin-left: calc(50% - #{$treeview-indent-line-width-half})
+      margin-inline-start: calc(50% - #{$treeview-indent-line-width-half})
       border-bottom-left-radius: $treeview-indent-line-border-radius
 
+      @include tools.rtl()
+        border-bottom-left-radius: 0
+        border-bottom-right-radius: $treeview-indent-line-border-radius
+
       &:last-child
-        margin-right: $treeview-indent-line-leaf-margin-right
+        margin-inline-end: $treeview-indent-line-leaf-margin-right
 
   .v-treeview-group.v-list-group
     --list-indent-size: 0px