[FIX] web: make emoji dropdown appear on top of content

Form sheet with hidden overflow (added to improve ribbon widget css) prevents
emoji button from showing emoji list when clicked. This commit attempts to
show the complete emoji dropdown by removing overflow from the sheet container.

IMPORTANT : This override won't affect ribbon since the hidden overflow was
added on the widget itself.

Task ID-2224393
PR #49096

addons/web/static/src/scss/form_view_extra.scss

@@ -16,7 +16,6 @@
             border: 1px solid #c8c8d3;
             box-shadow: 0 4px 20px rgba(0,0,0,0.15);
             background: white;
-            overflow: hidden;
 
             margin: $o-sheet-vpadding*0.2 auto;
             @include media-breakpoint-up(md) {