Introduce timoni bundle vet command

[stefanprodan]

The timoni bundle vet command validates that a bundle and its runtime definition conforms with Timoni's schema.

To verify that one or more CUE files contain a valid Bundle definition:

timoni bundle vet -f bundle.cue -f extras.cue -r runtime.cue

If the validation passes, Timoni will list all the instances found in the computed bundle.

When --print-value is specified, Timoni will write the Bundle computed value to stdout:

timoni bundle vet -f bundle.cue --runtime-from-env --print-value

Printing the computed value is particular useful when debugging runtime attributes.