fix(material/snack-bar): add max height for snack bar

Adds a max height for the snack bar in case users pass huge strings into it.

Fixes #31996.

Author: crisbeto

src/material/snack-bar/snack-bar-container.scss

@@ -30,13 +30,15 @@ $fallbacks: m3-snack-bar.get-tokens();
 }
 
 .mat-mdc-snack-bar-container {
-  display: flex;
-  align-items: center;
-  justify-content: center;
   box-sizing: border-box;
   -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
   margin: 8px;
 
+  // Note: ideally we would put this on the label,
+  // but it ends up breaking somewhat breaking internally.
+  max-height: 50vh;
+  overflow: auto;
+
   .mat-mdc-snack-bar-handset & {
     width: 100vw;
   }