fix: anchor tag safety (via #4789)

* v3.17.6

* release(3.17.6): rebuild dist

* add failing tests

* fix Link component

* fix OnlineValidatorBadge component

* switch from <a> to <Link> in operation components

* make Markdown inputs safe

* use Link component in Info block, for target safety

* add eslint rule for unsafe `target` usage

src/core/components/online-validator-badge.jsx

@@ -54,7 +54,7 @@ export default class OnlineValidatorBadge extends React.Component {
         }
 
         return (<span style={{ float: "right"}}>
-                <a target="_blank" href={`${ sanitizedValidatorUrl }/debug?url=${ encodeURIComponent(this.state.url) }`}>
+                <a target="_blank" rel="noopener noreferrer" href={`${ sanitizedValidatorUrl }/debug?url=${ encodeURIComponent(this.state.url) }`}>
                     <ValidatorImage src={`${ sanitizedValidatorUrl }?url=${ encodeURIComponent(this.state.url) }`} alt="Online validator badge"/>
                 </a>
             </span>)