Allow to connect with gocloud to AWS/GCP instances.

[ademariag]

Following what has already happened in https://github.com/cyrilgdn/terraform-provider-postgresql/pull/29 I would like to suggest to add support for connecting natively to GCP (and AWS/Azure) postgres/mysql instances without the need to use use a proxy by leveraging https://gocloud.dev/

I have done an initial test and it seems to work nicely with usql.

If I were to send a patch, would you want me (for postgres driver for instance) to create a new driver, or reuse the current one and add gcppostgres as an alias?

Regards Alessandro

[kenshaw]

@ademariag always open to PRs that are well written. I'm not sure how you'd be able to not use some kind of a proxy, which on the surface appears that's what the GoCloud SDK is doing (or some lazy variation of that).

[ademariag]

@kenshaw please let me know what you think about my proposed solution