take over table page for _dss_crawl table

[cldellow]

eg http://localhost:8001/test/_dss_crawl

Small tweaks:

• add link to http://localhost:8001/test/_dss_crawl/new, which will render a page to add a new crawl
• suppress Advanced export section
• suppress schema section
• hide config column? (or style it to truncate unless user clicks a checkbox? maybe https://docs.datasette.io/en/stable/plugin_hooks.html#render-cell-row-value-column-table-database-datasette would help)
• suppress "View and edit SQL"
• suppress "This data as json, etc"