Robot framework: add CLI plugin to generate configuration file (rebased onto dev_5_0)


This is the same as gh-3120 but rebased onto dev_5_0.

----

In preparation of the reactivation of the Robot framework jobs in our daily workflow, this PR adds modification allowing these tests to be run against an existing deployed CI integration servers.

A new  CLI plugin is created within the `components/tests/ui/plugins` folder with a `config` subcommand which generates Robot configuration file from a template file, the server settings and the `ice.config` file. The command should read as:

```
dist/bin/omero --path components/tests/ui/plugins robot config > components/tests/ui/resources/config.txt
```

The user/password to use for tests can be changed by using the `ICE_CONFIG` environment variable to any `ice.config` file on the system.

This PR should be tested:
- locally against a development server to verify the configuration is not broken
- on the CI infrastructure to test the web prefix logic is supported.

Note this PR does not fix currently failing Web tests. These will be fixed once the job is reactivated.

/cc @will-moore @jburel @aleksandra-tarkowska