Show message if devfile is invalid before creating a workspace
## Goal
Improve user experience by providing immediate feedback on devfile validity when creating a workspace, preventing errors before form submission.
## Problem
Currently, devfile validation only occurs after the user submits the form to create a workspace. This means users only discover invalid devfiles after waiting for form submission.
## Links
- https://summerofcode.withgoogle.com/organizations/gitlab/projects/details/Y9R088Nb
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