feat: allow defining a database name for a restricted user (joe#124)

Description

Allow defining a database name for a restricted user

Related issue

joe#124

Examples

DBLab CLI

dblab clone create --username john --password test --restricted --db-name test

POST /clone

{
  "db": {
    "username":   "john",
    "password":   "test",
    "restricted": true,
    "db_name": "test"
  }
}

Checklist

• the MR description has been reviewed
• this MR contains text changes and they have been reviewed OR there are no texts changes
• this MR contains GUI/CLI changes and they have been reviewed OR there are no GUI/CLI changes
• this MR contains API changes, specifications reflect those changes and they have been reviewed OR there are no API changes

Closes #124 (closed)