Che-IDEA should support opening a terminal into a sidecar container

[azatsarynnyy]

Is your enhancement related to a problem? Please describe

When the user starts a workspace from a typical Devfile with a database,
(e.g.: https://github.com/che-samples/java-spring-petclinic/blob/devfilev2/devfile.yaml)
he/she needs to open a terminal into more than one container.

But Che-IDEA supports a terminal for the editor's container only.
So, there's no way to execute a command in a DB container's terminal.

Describe the solution you'd like

It can be a plugin that adds the support for opening a terminal into the specified sidecar container using the machine-exec component. Like Che-Theia and Che-Code do.

Describe alternatives you've considered

As this task is quite complex, first, we need to investigate how it can be implemented, e.g.: plugin API, some 3-rd party libraries, etc.

Additional context

The related issue:

• Che-IDEA should support a target container when running a Devfile Command #21139

[l0rd]

@azatsarynnyy @vzhukovs if we could copy JetBrains IDEs and their dependencies in a volume and then execute it in the devfile container we would (partially) solve this problem. And we would make it work as VS Code. Is there a separate issue for this?

[azatsarynnyy]

@l0rd it was done within #20863

[azatsarynnyy]

and for DS 3.0 https://issues.redhat.com/browse/CRW-2736

[l0rd]

@azatsarynnyy great!

[l0rd]

So I am closing #21354