Support connect argument from MikroORM.init()

[grimurd]

Is your feature request related to a problem? Please describe.

When testing it can be useful to initial MikroORM without connecting to a database. MikroORM supports this through the connect argument in MikroORM.init().

Currently the nestjs module doesn't support this.

Describe the solution you'd like

Either add a argument to MikroORMModule.forRoot()/forRootAsync() or add it to the module options object.

[B4nan]

connect will be a regular configuration option too since v5.0.3 of the ORM (no changes in the nest adapter, just upgrade the ORM)