Add ability to specify the container environment

[pditommaso]

When a Wave request is submitted, the ContainerConfig can be used to specify the environment to be used in the target Wave container.

The goal of this ticket to add a command line option --config-env that allows the user to specify the environment of the corresponding request.

The environment should be provided as key-value pair specified as a string with the syntax NAME=VALUE. The --config-env option can be repeated as many times as need to provide multiple env variables e.g

wavelit --config-env FOO=one --config-env BAR=two