Add icon for tar-installed extensions

### Bug description

`inspect_image_labels()` has no icon field. Store logos come from the extensions-repo `metadata.json` URL. A tar install has none.

### Steps to reproduce

1. Install an extension from a .tar on 1.5
2. Open the Installed list

### Primary pain point(s)

Local extensions show with no logo.

### Additional context

https://discuss.bluerobotics.com/t/adding-icons-to-locally-installed-blueos-extensions/22897

### Prerequisites

- [x] I have checked to make sure that a similar request has not already been filed or fixed.

Start by tracing inspect_image_labels() to the Installed list and compare its data with the extensions-repo metadata.json icon URL. Verify how tar-installed extensions are represented, then confirm that a locally installed extension displays an icon in the Installed list without breaking store-installed extensions.

Written by the indexing model from the issue text.