Generalize Time Series Viewer to use without sample points layer

[valpasq]

The current version of the Time Series Viewer assumes the user will provide an asset (point geometry) for interpretation, with the option to pull time series on-the-fly or from an asset with cached time series values.

Suggested options/decision points:

• Sample dataset? (Y/N)
  • N: Prompt to begin exploring map, click to load TS
  • Y: Load cached asset? (Y/N)
    - N: Specify asset with sample locations
    - Y: Specify asset with sample locations + cached TS (option to run cache?)