Provide a more informative error when supplying an invalid API URL

[ejseqera]

When providing an invalid endpoint URL either through setting TOWER_API_ENDPOINT or with the --url/-u option, the CLI raises a non-informative error.

> tw -u https://wrong.cloud.seqera.io/api launch --name hello-world --workspace seqera/showcase --compute-env seqera_aws_ireland_fusion_nvme --labels aws hello

 ERROR: error

Alternatively:

> export TOWER_API_ENDPOINT=https://wrong.cloud.seqera.io
> tw launch --name hello-world --workspace seqera/showcase --compute-env seqera_aws_ireland_fusion_nvme --labels aws hello

 ERROR: error

Other endpoints seem to return a more informative error but it would be helpful for this to be consistent for all subcommands:

> tw -u https://wrong.endpoint/api workspaces list

 ERROR: java.net.UnknownHostException: wrong.endpoint


 ERROR: Connection error. Check the connection using the command 'tw info'.

Version info:

    Details
   -------------------------+-----------------------------
    Tower API endpoint      | https://api.cloud.seqera.io
    Tower API version       | 1.25.0
    Tower version           | 24.2.0_cycle28
    CLI version             | 0.10.3 (a86eeed)
    CLI minimum API version | 1.15
    Authenticated user      | eshajoshi

   System health status
   ---------------------------------------+----
    Remote API server connection check    | OK
    Tower API version check               | OK
    Authentication API credential's token | OK