Display correct app identifier for apps

### What Happened?

In the dashboard, my app’s identifier is listed as `com.github.small-tech.comet`.

It looks like this is calculated from the repository URI and not from the actual app identifier, which has two issues:

1. For GitHub-based app identifiers, it does not perform the character substitutions necessary to conform to DBus conventions. (In the example, above, if I was using a GitHub reverse-domain, the identifier should be `com.github.small_tech.comet` (note the underscore, not the dash) as dashes are only allowed in the last segment of the identifier.

2. For non-GitHub-based app identifiers, the identifier is entirely incorrect which might lead people to think that there is something wrong in their configuration.

### Steps to Reproduce

See above.

### Expected Behavior

The correct app identifier should be shown. This will require it to be parsed from the repository.

### OS Version

6.x (Odin)

### Software Version

Latest release (I have run all updates)

### Log Output

```shell
n/a
```

### Hardware Info

n/a