Allow to configure the vhost in the connection settings too

[stof]

Currently, most commands expect a connection name and a vhost. It would be great to be able to specify the vhost in the connection config file too (making the command-line argument required only when the config file does not configure it). This is especially useful when your connection credentials give you access to only 1 vhost (this is what happens for hosted RabbitMQ providers), where using a different vhost requires using a different connection anyway.

This may require a BC break to switch the vhost from an argument to an option though.

[stof]

what do you think @odolbeau ?

[Shine-neko]

ping @odolbeau

[odolbeau]

Looks like I missed a lot of PR / issues right here, sorry for that. :/

Looks fine for me! 👍