Add support for VSCode remote development

[luckyf]

This feature enables developers a fast and easy start with the new Remote Container Development feature of VSCode.

To getting started:

1. Install the "Remote Development" extension pack (ms-vscode-remote.vscode-remote-extensionpack)
2. Copy "/dev/docker-postgres/sample.yml" to "/config.yml"
3. Open Workspace in Container

This feature uses the postgress docker development strategy.
Resolves my feature request from last year.

@NGPixel: I also can provide a more detailed introduction in the docs.

[NGPixel]

Made some changes so that the dockerfile, compose and config are inside the dev/containers folder. Putting these files at the root of the project is dangerous as many people will try to run them thinking it's for production.

Also updated the dev documentation to reflect this change:
https://docs.requarks.io/en/dev

Thanks!

[luckyf]

You're right.
My intention was not to change too much to get this feature accepted.
Thank you very much for the work!