start and end times are not computed as per expectations

[sravankorumilli]

Description :

• truncate by week and month instead of truncating to end instead of start interval.
• monthly window end is ending a day short.
• the assumption of 30 days window size as a month isn't logical instead user can just define the window with M notation for windowing.

Acceptance Criteria :

• [ ] Provide a correct implementation with backward compatible support for the existing version.
• [ ] Have default version as version 2 on spec creation.

[sravankorumilli]

Some Existing Concerns which we need to address along with the current issue.

1. TaskWindow message in compileAssets RPC has to be updated to accept start and end times.
2. Persist window inputs as is in the Database instead of storing the modified inputs