Make AIO app init process more intuitve

For the `aio app init` process I'd be happy to see that all app types are handled consistently in the interactive mode, because CLI options (such as `--standalone-app`) are more for experienced users. New users should be guided properly without having to know those CLI options (or that there are different ways to create an app to begin with).

This means that the first step in the init should ask the user if they want to create a standalone app (which probably is the most often used app type) or if they want to create an app from a template. When template option is selected the available templates would be ideally sorted by 'most used', arguably/probably with the EXCShell extension template as the default on top, which would also guide users to what they most likely want. Currently it's in last position and sometime not even visible until the user 'scrolls' down with the arrow keys (which already confused some users).

In addition, the description of the EXCShell app is not really informative, it says 'template for generator-aio-app'. I don't know what this is. Better would be something like 'template for Experience Cloud apps with UI' or similar.

### Expected Behaviour
The init process of a new app is not confusing, intuitive and consistent, i.e. all types of apps can be created in guided interactive mode. The most used app types are prominent on top of the list.

### Actual Behaviour
The app init process is inconsistent and confusing (standalone only via CLI option) and otherwise interactive with templates

### Reproduce Scenario (including but not limited to)
Initialization of a new AB app

#### Steps to Reproduce
`aio app init`

#### Platform and Version
All

#### Sample Code that illustrates the problem
`aio app init`
`aio app init --standalone-app`

Start by running `aio app init` and `aio app init --standalone-app` to inspect the current interactive flow and template list. Trace the CLI entry point for app initialization and the template-selection prompts. Done means interactive mode offers standalone and template apps, presents the most-used templates prominently, and uses an informative EXCShell description.

Written by the indexing model from the issue text.