Add support to create new table in the database

[grabdoc]

1. Add a new parameter ENABLE_DB_MIGRATION = true | false
2. The request payload structure

tableName: t_employee
description: Employee table
columns : [
{
name : 'id'
description: 'Id column'
type: 'string'
length: 30
pk: true
}
,
{
name : 'first_name'
type: 'string'
length: 30
nullable: false
}
,
{
name : 'age'
type: 'int'
defaultValue: 0
}
,
.....

]