Created selection-flag start and end flag (#380)

* Created selection-flag start and end flag

* Update icons/selection-flag-start.svg

Co-authored-by: Eric Fennis <eric.fennis@gmail.com>

* Update icons/selection-flag-end.svg

Co-authored-by: Eric Fennis <eric.fennis@gmail.com>

* Rename selection-flag-start.svg to flag-triangle-right.svg

* Rename selection-flag-end.svg to flag-triangle-left.svg

Co-authored-by: Eric Fennis <eric.fennis@gmail.com>

icons/flag-triangle-left.svg

@@ -0,0 +1,13 @@
+<svg
+  xmlns="http://www.w3.org/2000/svg"
+  width="24"
+  height="24"
+  viewBox="0 0 24 24"
+  fill="none"
+  stroke="currentColor"
+  stroke-width="2"
+  stroke-linecap="round"
+  stroke-linejoin="round"
+>
+  <path d="M17 22 17 2 7 7 17 12" />
+</svg>

icons/flag-triangle-right.svg

@@ -0,0 +1,13 @@
+<svg
+  xmlns="http://www.w3.org/2000/svg"
+  width="24"
+  height="24"
+  viewBox="0 0 24 24"
+  fill="none"
+  stroke="currentColor"
+  stroke-width="2"
+  stroke-linecap="round"
+  stroke-linejoin="round"
+>
+  <path d="M7 22 7 2 17 7 7 12" />
+</svg>