MINOR: log: introduce log_orig flags

MINOR: log: introduce log_orig flags

Rename 'enum log_orig' to 'enum log_orig_id', since this enum specifically
contains the log origin ids.

Add 'struct log_orig' which wraps 'enum log_orig' with optional flags
(no flags defined for now).

Add log_orig() helper func that takes id and flags as parameter and
returns log_orig struct initialized with input arguments.

Update functions taking log origin as parameter so they explicitly take
log orig id or log orig wrapper as argument depending on the level of
context expected by the function.