STCOM-1392 Use h3 instead of h1 for menu. (#2405)

We saw it coming. We did. Zak should've pressed me. We should have
changed the default `labelTag` back then, in
[STCOM-1191](https://folio-org.atlassian.net/browse/STCOM-1191). Despite
so much documentation around the internet regarding the `<section>` tag
and its contained heading supporting `h1-h6`, etc... there's a scarce
amount of connection to the safety-first best-and-long-practiced pattern
of ONE SINGLE H1 PER-PAGE! (regardless of visiblity status.) Regardless
of what apparent outcome of articles like this ([`h2` is the apparent
ceiling for `sections`,
period](https://www.webucator.com/article/html-heading-levels-and-sectioning-content/))
Having multiple `<H1>`'s show up to any validator and expecting
validators/audit tools of any kind to read the minds of browsers/browser
developers/spec writers/developers
everywhere... just set it to make sense if you view the mark-up. Since
dropdowns are commonly used within panes (which conventionally hold
`h2`'s as their header) defaulting to `h3` fits with the convention.

CHANGELOG.md

@@ -15,6 +15,7 @@
 * Wrap `<Card>`'s render output in `<StripesOverlayContext>` to facilitate ease with overlay components. Refs STCOM-1384.
 * Clear filter value after an action chosen from `MultiSelection` menu. Refs STCOM-1385.
 * ExportCSV - fix usage within `<Modal>`s by rendering the download link to the `div#OverlayContainer`. Refs STCOM-1387.
+* `<MenuSection>` should default its heading/label tag to `H3` instead of `H1`. Refs STCOM-1392.
 
 ## [12.2.0](https://github.com/folio-org/stripes-components/tree/v12.2.0) (2024-10-11)
 [Full Changelog](https://github.com/folio-org/stripes-components/compare/v12.1.0...v12.2.0)

lib/MenuSection/MenuSection.js

@@ -9,7 +9,7 @@ import uniqueId from 'lodash/uniqueId';
 import css from './MenuSection.css';
 import Headline from '../Headline';
 
-const MenuSection = ({ className, children, id, label, labelTag = 'h1', ...rest }) => {
+const MenuSection = ({ className, children, id, label, labelTag = 'h3', ...rest }) => {
   const sectionId = id || uniqueId('menu-section-');
   return (
     <section