Enhance logs to include timestamp data to provide timestamp for timestamp toggle filter

[veds-g]

Logs emitted by different vertex do not have a uniform format. For some vertices timestamp data is present in the log object, but for others it is appended as a string in the beginning.
This caused the issue #2342
Example - for a simple pipeline
cat vertex has ts object in the logs to determine timestamp

sink vertex has log appended in the beginning as a string causing difference in format