This special purpose UI provides commands that can benefit from direct
access to the io.Reader and io.Writers of the base cli.Ui. It can
traverse a chain of ColoredUis to find the base. Currently, it can
retrieve writers from a cli.BasicUi (or cli.MockUi for testing).
Renames ui.go and ui_test.go to log_ui.go and log_ui_test.go
This update changes the behaviour when following logs from an
allocation, so that both stdout and stderr files streamed when the
operator supplies the follow flag. The previous behaviour is held
when all other flags and situations are provided.
Co-authored-by: Luiz Aoqui <luiz@hashicorp.com>
