Error injection class is implemented in order to allow injecting
various errors (exceptions, stalls, etc.) in code for testing
purposes.
Error injection is enabled via compile flag
SCYLLA_ENABLE_ERROR_INJECTION
TODO: manage shard instances
Enable error injection in debug/dev/sanitize modes.
Unit tests for error injection class.
Closes#3295
Signed-off-by: Pavel Solodovnikov <pa.solodovnikov@scylladb.com>
Signed-off-by: Alejo Sanchez <alejo.sanchez@scylladb.com>
