(core) Adding colors to toast notification

Summary:
Styling toast notification. Adding colors and icons.
In Grist, changed the default style for errors (will be shown in red), and a style for
Linked copied to clipboard (will be shown in Green).
All other colors are not used currently, left for another diff.

Test Plan: manual

Reviewers: georgegevoian

Reviewed By: georgegevoian

Differential Revision: https://phab.getgrist.com/D3053

static/ui-icons/UI/Warning.svg

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   id="svg8"
+   version="1.1"
+   viewBox="0 0 16 16"
+   height="16px"
+   width="16px">
+  <title
+     id="title895">Icons / UI / Warning</title>
+  <g
+     id="g4"
+     transform="matrix(0.13020927,0,0,0.13020927,-3.3723964e-5,1.6645866)">
+    <path
+       id="path2"
+       d="m 65.45,1.972 55.594,87.323 c 1.673,2.63 3.117,8.016 0,8.016 H 1.837 c -3.118,0 -1.676,-5.386 0,-8.016 L 57.431,1.972 c 1.675,-2.63 6.343,-2.628 8.019,0 z m -8.872,72.174 h 9.682 v 8.561 h -9.682 z m 9.676,-5.929 H 56.58 C 55.616,56.461 53.598,49.001 53.598,37.262 c 0,-4.331 3.51,-7.842 7.841,-7.842 4.332,0 7.842,3.511 7.842,7.842 10e-4,11.734 -2.045,19.209 -3.027,30.955 z"
+       style="clip-rule:evenodd;fill-rule:evenodd" />
+  </g>
+</svg>