feat: add a cascade option to drop_database (#4697)

The remote catalog could only drop an empty database: it always asked
the server for a restricted drop.

`DropDatabaseRequest::cascade`, `drop_database(..., cascade=True)` in
Python and `dropDatabase(name, { cascade: true })` in TypeScript ask the
server to drop everything in the database first. The name stays taken
until the server finishes cleaning up the dropped objects' storage. A
restricted drop remains the default.

docs/src/js/classes/Catalog.md

@@ -70,7 +70,9 @@ Create a database, or open an existing database when existOk is true.
 dropDatabase(name, options): Promise<void>
 ```
 
-Drop an empty database. The server rejects nonempty databases.
+Drop a database. A nonempty database is an error unless `cascade` is set,
+which drops everything in it first; the name stays taken until the server
+finishes cleaning up their storage.
 
 #### Parameters
 
@@ -78,6 +80,8 @@ Drop an empty database. The server rejects nonempty databases.
 
 * **options** = `{}`
 
+* **options.cascade?**: `boolean`
+
 * **options.ignoreMissing?**: `boolean`
 
 #### Returns