Add Discovery Server setting in the UI

[MMarcus95]

This PR adds the possibility to discover and visualize topics in Plotjuggler when using Discovery Server setting.

The UI has been changed as follows

How to use

As in the current behavior, when the Select DDS message window appears, by default a domain participant in the Current DomainId domain is created, which uses Simple Discovery.

To allow Plotjuggler to discover topics when using Discovery Server setting you need to:

• set the server ip in the server IP field
• set the server port in the server port field
• enable the Discovery Server setting by clicking on the button OFF

Once the Discovery Server setting is enable, you will see:

• the button changing to ON
• the Change Domain button becoming gray, meaning that when the Discovery Server setting is ON you cannot use Simple Discovery, avoiding to mix incompatible discovery settings

When the Discovery Server setting is turned off by clicking the ON button, a domain participant is created in the Current DomainId domain using Simple Discovery and the possibility use Simple Discovery and to change the domain is restored.

Notice that server IP and server port need to be set before starting the discovery server, so when the button is in OFF state.

[juanlofer-eprosima]

@MMarcus95 Thanks for your contribution! We will be allocating some time in the next days to review your PR.