Allow disabling fallback for detect commands

[reegnz]

Is your feature request related to a problem? Please describe.
I need to determine if a folder has tofu or terraform configured for it. If tofu version file is present I run tofu commands, if terraform version file is present I run terraform commands.
tenv tofu detect almost seems like the right command, but if it fails finding version files, a fallback strategy is triggered to select a tofu version, and the exit code of the command will be 0.

Describe the solution you'd like
tenv tofu detect --no-fallback command, that fails if no version files are found for tofu, and the command exits with a non-zero exit code.
tenv tf detect --no-fallback command, that fails if no version files are found for tofu, and the command exits with a non-zero exit code.
etc.

Describe alternatives you've considered
Parsing stdin for the message "No version files found".

Additional context