Crash when rendering template fails during project creation

[m-alisafaee]

Describe the bug
We try to render all project files as Jinja templates when initializing a project. If a files isn't a valid Jinja template then the rendering fails causing the project creation to fail.

To Reproduce
renku init -s https://gitlab.renkulab.io/mohammad.alisafaee/ammo-template -r 8fe97f4 test

Expected behavior
If a file cannot be rendered, we should catch the error and print a warning for users and allow the project creation to continue.

We can also mark some files as not-to-be-rendered in the template manifest but this requires more work on the user side and makes template creation more complex.

Additional context
https://renku.discourse.group/t/unable-to-create-a-renku-project-from-a-custom-renku-template-and-a-specific-commit/