As a Bendini user I want to be able to follow output when executing a function

[abbec]

Description

Currently, we use files to do stdout/stderr redirection in Avery. We should instead create a struct that implements WasiFile and can read stdout/stderr pipes and then write to file and stream to network.

Acceptance Criteria

• Bendini has a --follow flag that shows output (stdout+stderr) of the running function
• The --follow flag works over the network. I.e. the function is executed on another computer than bendini.