Add html lang prop to CodeEditor Component inside the SourceCodeModal (#2043)

src/editors/sharedComponents/SourceCodeModal/__snapshots__/index.test.jsx.snap

@@ -41,6 +41,7 @@ exports[`SourceCodeModal renders as expected with default behavior 1`] = `
   >
     <injectIntl(ShimmedIntlComponent)
       innerRef="moCKrEf"
+      lang="html"
       value="mOckHtMl"
     />
   </div>

src/editors/sharedComponents/SourceCodeModal/index.jsx

@@ -1,4 +1,3 @@
-import React from 'react';
 import PropTypes from 'prop-types';
 
 import {
@@ -41,6 +40,7 @@ const SourceCodeModal = ({
         <CodeEditor
           innerRef={ref}
           value={value}
+          lang="html" // hardcoded value to do lookup on CODEMIRROR_LANGUAGES
         />
       </div>
     </BaseModal>