Add support for multiple TFMs `<TargetFrameworks>`

Context:

Some templates (`fluentuiblazorwasm`, `fluentuiblazorserver`) use `` which causes following error:

```
Unable to run your project
Your project targets multiple frameworks. Specify which framework to run using '--framework'.
```

In Dashboard 2 endpoints appear, but apps are not started.

Reducing TFMs to 1 does not help (and multiple endpoints are not removed from Dashboard):

```xml
net8.0
```

Not even switching to single TFM (singular) and nuking `bin/` and `obj/` folders:

```xml
net8.0
```

Templates:

`fluentuiblazorwasm`

```

3.6.0
3.6.0.24067
3.6.0.24067
3.6.0.24067


net6.0;net7.0
enable
enable
true

```

`fluentuiblazorserver`

```

3.6.0
3.6.0.24067
3.6.0.24067
3.6.0.24067


net6.0;net7.0
enable
enable
true

```