Extend the idea of error hash signatures and use it to identify the
parse results of states as well. Each state may define a set of
'signature fields' and, after the parsing is done and the data is
collected, these fields will be used to identify the result set and
generate a unique hash string for them.

These signatures aren't necessarily related to errors, they simply
represent a result.

For now, the new states '_summary', '_signature_fields' and '_signature'
are defined as hidden and are invisible unless the `--json-full` flag is
used.

This change also moves the hash generation to a common utility function.

Signed-off-by: Ricardo Cañuelo <[email protected]>

Signed-off-by: Ricardo Cañuelo <[email protected]>

Signed-off-by: Ricardo Cañuelo <[email protected]>

Signed-off-by: Ricardo Cañuelo <[email protected]>

Signed-off-by: Ricardo Cañuelo <[email protected]>

Signed-off-by: Ricardo Cañuelo <[email protected]>

Signed-off-by: Ricardo Cañuelo <[email protected]>

Add a state data field: linux.boot.kernel_started that will be True if
the parser detects at least one line of kernel log and False if it
doesn't.

Signed-off-by: Ricardo Cañuelo <[email protected]>

Signed-off-by: Ricardo Cañuelo <[email protected]>

Add a summary message for the scenario where the parser can't detect any
kernel output. With this into place, the possible result cases for this
state are:

1) Kernel booted ok and reached a prompt:
   _summary = Linux boot prompt found
2) Kernel produced no output at all:
   _summary = Kernel didn't start
3) Kernel started to load but didn't reach a prompt:
   _summary = Linux boot prompt not found

Signed-off-by: Ricardo Cañuelo <[email protected]>