Wrap output for customization. Move all output handling to a single managing class.
Wrap output for customization. Move all output handling to a single managing class.

Instead of passing the output parameters to std::cout straight away, use
helper wrappers. This will allow us to add more formats for gathered
tests results.

Introduce helper writer classes hierarchy that can be extended to
support different output formats (JSON, XML, etc).

Signed-off-by: Vladimir Krivopalov <dc9186a06078733915a6fcbab34e59120be2b484@scylladb.com>

avikivity/scylla,avikivity/scylla,duarten/scylla,duarten/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla