[UX] Block charm on deployment with a message "This charm is NOT meant to be deployed as Juju application."

Hi,

It is a UX proposal, this charm is not supposed to be deployed, but confusing results achieved if done by mistake:
```
ubuntu@juju3:~$ juju status
Model Controller Cloud/Region Version SLA Timestamp
demo18 microk8s microk8s/localhost 3.1.6 unsupported 18:07:42+01:00

App Version Status Scale Charm Channel Rev Address Exposed Message
data-platform-libs waiting 1 data-platform-libs stable 26 10.152.183.245 no installing agent

Unit Workload Agent Address Ports Message
data-platform-libs/0* unknown idle 10.1.141.221
```

Proposal: block charm with the information: This charm is NOT meant to be deployed as Juju application.

```
ubuntu@juju3:~$ juju status
Model Controller Cloud/Region Version SLA Timestamp
demo18 microk8s microk8s/localhost 3.1.6 unsupported 18:07:42+01:00

App Version Status Scale Charm Channel Rev Address Exposed Message
data-platform-libs blocked 1 data-platform-libs stable 26 10.152.183.245 no This charm is NOT meant to be deployed as Juju application.

Unit Workload Agent Address Ports Message
data-platform-libs/0* blocked idle 10.1.141.221 This charm is NOT meant to be deployed as Juju application.
```

Low priority UX improvement.