added extend lease thread capabilities

[dorzeidman]

Changes:

• added extend_lease_interval property to WorkerInterface.
• TaskHandler: if extend_lease_interval > 0: a thread will be created that will send every extend_lease_interval seconds a task update call with extendLease = true flag, the task won't be rescheduled by the Conductor unless (extendLease must be lower than responseTimeoutSeconds

Reason:
I need to run long running task (a few hours) and I want to use the extendLease = true feature to have the worker extend lease every few minutes.

[AlonSpitz]

Hi, that's a valuable feature. what's the status on this PR?

[dorz-saymine]

@v1r3n did you check my pr?

[v1r3n]

Hi @dorz-saymine thanks for the PR. We have another PR in progress that should address this. Stay tuned and I can share the branch if you would like to test it out and provide your take/feedback.