Set welcome message for the stack in the template schema

[shreyas-goenka]

Changes

Sets welcome_message instead of including it in the prompt for the first question

Note, we need a new CLI release and need to set min_cli_version before this can be merged!

Tests

Tested manually.
The UX remains identical:

shreyas.goenka@THW32HFW6T mlops-stack % cli bundle init ~/mlops-stack
Welcome to MLOps Stacks. For detailed information on project generation, see the README at https://github.com/databricks/mlops-stacks/blob/main/README.md.

Project Name [my-mlops-project]:

[arpitjasa-db]

LGTM thanks @shreyas-goenka !