Simplify definition of window for a job

[sbchaos]

Description
Current definition of a window uses time.Duration as base for all the calculations, which leads to optimus storing window configuration in nanosecond for both size and delay. Also the time.Duration does not provide way to deal with quantities greater than hour to not deal with timezones.

With this we will also expose presets for end user to define window in a simple manner.
eg @hourly, @daily etc so that people can reason about window properties.

Acceptance Criteria

• Define simpler units for window e.g. 1d, 1w etc
• Define presets for window definition

Depends on : 571

Tech Details
Post analysis Capture the details of the work needed to finish the task.

• Create a new version of window configuration
• Changes in optimus to store the presets in database