Fix record page opensearch_catalog_url error

Related to #452 (closed)

Getting an error when trying to load a record page, for example:

http://localhost:3001/record/nge_ngen_brotherhood-march

Showing /home/seanp/.rbenv/versions/2.7.6/lib/ruby/gems/2.7.0/gems/blacklight-7.30.0/app/views/layouts/blacklight/base.html.erb where line #12 (closed) raised:

undefined method `opensearch_catalog_url' for #<#<Class:0x00007fb378d50a38>:0x00007fb379f22a68>
Did you mean?  opensearch_records_url
Extracted source (around line #12):
             

    <title><%= render_page_title %></title>
    <%= opensearch_description_tag application_name, opensearch_catalog_url(format: 'xml') %>
    <%= favicon_link_tag %>
    <%= stylesheet_link_tag "application", media: "all" %>
    <%= javascript_include_tag "application" %>

Trace of template inclusion: #<ActionView::Template /home/seanp/.rbenv/versions/2.7.6/lib/ruby/gems/2.7.0/gems/blacklight-7.30.0/app/views/layouts/catalog_result.html.erb locals=[]>