add bootstrap icons (#26980)

* add bootstrap icons

* pin
old-commit-hash: 657f1c1337

third_party/bootstrap/.gitignore

@@ -0,0 +1 @@
+/icons/

third_party/bootstrap/bootstrap-icons.svg

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:d7ecfaac355e51c9b95319fdf4681cf4c423109fd477e961af588b92607a76da
+size 1087239

third_party/bootstrap/pull.sh

@@ -0,0 +1,14 @@
+#!/bin/bash
+set -e
+
+DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" >/dev/null && pwd )"
+cd $DIR
+
+if [ ! -d icons/ ]; then
+  git clone https://github.com/twbs/icons/
+fi
+
+cd icons
+git fetch --all
+git checkout d5aa187483a1b0b186f87adcfa8576350d970d98
+cp bootstrap-icons.svg ../