Set migration-dir or scope / internals.migrationMode from config with -e option?

Hi just trying to figure out how to use db-migrate in a simple way.
I have a database.json in a config directory, postgresql so a connection string for a user that has ownership of a database schema I want to work with.

Is there a way to do something like this?

database.json
```json
{
"myConnection":
{
"connectionString": "etc...",
"migrationMode": "myMode",
"migrations-dir": "./migrations/myConnection"
}
}
```

So that when I do

```bash
db-migrate create something
```

It would create in

`./migrations/myConnection/myMode/date-something.js`

Or even just a migration directory setting per connection config would be nice.

`./migrations/myConnection/date-something.js`

I feel writing so much is not ideal would be nice to just write simple command to up or create new migration.
```bash
db-migrate create something --config=./config/database.json -v -e myConnection
```

Easier like this?
```bash
db-migrate create something -e myConnection
db-migrate up -e myConnection
```

Having it in database connection configs would allow to have multiple connections use the same migration scripts but have different databases/schemas.

---
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