If a column is payload or contains _payload it will be assumed
it has JSON data in it, then we will show the truncated JSON in the
result column with a button to show the full-screen formatted
JSON using our full-screen code viewer. We also do the same if
the column is the `json` postgres data type.
This commit updates the plugin to the latest guidelines, as shown in
discourse-plugin-skeleton, which involves moving a lot of the code to
dedicated files, use proper namespaces, use the autoloader as much as
possible, etc.
Before this fix, the use of PG template patterns containing ":" or the
use of "?" in comments in the SQL will result in an error being raised
because `DB.param_encoder.encode` calls ActiveRecord's `sanitize_sql_array` which is
meant for SQL fragments and not an entire SQL string.
Instead we change data-explorer to use `MiniSql::InlineParamEncoder`
instead which takes into account of template patterns and does not trip
on `?` which is a special param encoding character used by ActiveRecord.