Add ability to manage commands' targets

[slemeur]

As described in the specification #2681, we need to provide the ability to define the targets of a command.

In a multi-machine environment, the target defines on which machine(s) a command can be executed to.

The use will have the ability to define the list of machines where the command can be executed:

• by default, the command will be enabled to dev-machine of the environment

Command Palette
User is able to select a command:

• When the command is applicable to multiple machine, we ask the user the target where he wants to execute the command
• When the command is applicable to only one machine, we directly execute the command accross that machine

Run Button
When the user selects a command from the Run button:

• When the command is applicable to multiple machine, we ask the user the target where he wants to execute the command
• When the command is applicable to only one machine, we directly execute the command accross that machine

Right-click in process panel
We filter the commands by only those which are applicable to the selected machine.