feat(task, api): Timeseries Expressions

[dennisgsmith]

Description

Successor to #280

TODO:

• Implement compute job of full timeseries on timeseries expression create/update
• Implement partial compute when dependency is updated
• Validate compile time errors on expression cration
• Implement program cache to keep compiled expressions in memory for requently updated timeserires
• Implement expression DAGs to allow computed timeseries to be used as dependencies of other computed timeseries
• Performance and regression testing