UI/Feature: Show "View Suggested Solution" instead of / alongside "Send solution to server" for already completed exercises

[rubenmgoncalves]

Description of the issue:

When I solve an exercise, it passes all tests, and submit it to the server, it is correctly marked as completed. However, if I close the exercise and go back to it later, the TMC extension UI still prompts me to "Send solution to server" the exercise again.

Expected behavior:

If an exercise has already been successfully submitted and completed on the server, the extension should recognize this state. Instead of (or alongside) the "Send solution to server" button, it should give me the option to view the suggested/model solution. Currently, I cannot access the model solution (directly from the extension) for an exercise I return to because only the "Send solution to server" button is visible.

My Environment:

VS Code Version: 1.111.0
TMC Extension version: 3.5.1
OS: Linux - Fedora 43