Fix reading configuration from stdin when applying
Fix reading configuration from stdin when applying

This ensures that the entire contents of stdin is read into a buffer
before attempting to send it to butterfly by calling `read_to_end()`.

Signed-off-by: Jamie Winsor <b4dde37aa2aac745c0e6c43447507eaeace3e59f@vialstudios.com>

habitat-sh/habitat,habitat-sh/habitat,rsertelon/habitat,habitat-sh/habitat,rsertelon/habitat,habitat-sh/habitat,habitat-sh/habitat,habitat-sh/habitat,rsertelon/habitat,habitat-sh/habitat,rsertelon/habitat,rsertelon/habitat,habitat-sh/habitat,rsertelon/habitat,rsertelon/habitat