Open file link for new modal in new tab

The old finding modal opens file links in a new tab. This updates the
behavior of the new modal to also do this. While it's on the same
domain, we're leaving the current experience because going back would
not open the modal automatically.

Changelog: fixed
EE: true

ee/app/assets/javascripts/security_dashboard/components/shared/vulnerability_details_graphql/index.vue

@@ -320,7 +320,7 @@ export default {
           :label="$options.i18n.locationFileLabel"
           data-testid="location-file-list-item"
         >
-          <component :is="file.url ? 'gl-link' : 'span'" :href="file.url">
+          <component :is="file.url ? 'gl-link' : 'span'" :href="file.url" target="_blank">
             {{ file.name }}
           </component>
         </details-section-list-item>

ee/spec/frontend/security_dashboard/components/shared/vulnerability_details_graphql/index_spec.js

@@ -474,6 +474,7 @@ describe('ee/security_dashboard/components/shared/vulnerability_details_graphql/
 
             expect(fileLink.attributes('href')).toBe(`${blobPath}#L${expectedLineRange}`);
             expect(fileLink.text()).toBe(`${file}:${expectedLineRange}`);
+            expect(fileLink.attributes('target')).toBe('_blank');
           },
         );
       });