Add support in databases tab to create a new database

Currently in the databases tab you can view a list of databases on a trove instance and can delete a database but there is no support for adding a database

We should add support in this tab for creating databases on an instance in support of the following client command:

trove help database-create
usage: trove database-create <instance> <name>
                             [--character_set <character_set>]
                             [--collate <collate>]

Creates a database on an instance.

Positional arguments:
  <instance> ID of the instance.
  <name> Name of the database.

Optional arguments:
  --character_set <character_set>
                        Optional character set for database.
  --collate <collate> Optional collation type for database.