Implement acknowledgement for the compound config

[rouming]

This PR adds 'timestamp' and 'last_cmd_timestamp' fields. New fields have the following meaning (copied from the local_profile.proto):

     A list of commands requested to be executed for locally running application instances.
     A new request created for the same application should overwrite the previous entry
     with the 'timestamp' field updated. In other words, the list should contain at most
     one entry for each application instance.
     It is not required for the Local profile server to persist command requests.
     Also, it is not required for the Local profile server to stop submitting command
     requests that have been already processed by EVE. Using the `timestamp` field,
     EVE is able to determine if a given command request has been already handled or not.
     To check if the last requested command has completed, compare its timestamp with
     'last_cmd_timestamp' from `LocalAppInfo` message, submitted by EVE in the request

For the compound config message I change the order of all fields to have the sequence field to be the first. This is safe, because the structure is not in use anywhere.

[rouming]

Difference to the previous version:

• Create a separate message CompoundEdgeDevConfigRequest which includes the ConfigRequest and the ack_seq field.
• Code comments tweaks.

[rouming]

Difference to the previous version:

• rename cfgReq to cfg_req
• a few code comments tweaks

[rouming]

Difference to the previous version:

• Rename seq/ack_seq fields to timestamp/last_cmd_timestamp as requested by Erik