feat(icon): allow SVG icons to be registered from strings (#10757)

Expands the icon registry to allow for icons and icon sets to be registered using a trusted HTML string.

Fixes #3132.

Author: crisbeto

src/demo-app/icon/assets/core-icon-set.svg

@@ -9,10 +9,18 @@
     <mat-icon svgIcon="thumb-up"></mat-icon>
   </p>
 
+  <p>
+    From inline template with MatIconProvider:
+    <mat-icon svgIcon="bike" class="green"></mat-icon>
+    <mat-icon svgIcon="bike"></mat-icon>
+  </p>
+
   <p>
     Mirrored in RTL:
     <mat-icon class="mat-icon-rtl-mirror green" svgIcon="thumb-up"></mat-icon>
     <mat-icon class="mat-icon-rtl-mirror" svgIcon="thumb-up"></mat-icon>
+    <mat-icon class="mat-icon-rtl-mirror green" svgIcon="bike"></mat-icon>
+    <mat-icon class="mat-icon-rtl-mirror" svgIcon="bike"></mat-icon>
   </p>
 
   <p>
@@ -22,6 +30,13 @@
     <mat-icon svgIcon="core:alarm"></mat-icon>
   </p>
 
+  <p>
+    From inline icon set:
+    <mat-icon svgIcon="core-inline:account-balance"></mat-icon>
+    <mat-icon svgIcon="core-inline:account-balance-wallet"></mat-icon>
+    <mat-icon svgIcon="core-inline:account-box"></mat-icon>
+  </p>
+
   <p>
     Ligature from Material Icons font:
     <mat-icon>home</mat-icon>