Statistical Summary allows user to select invalid Time of Year

[rod-glover]

To reproduce:

1. Home/Data > Single Variable
2. Select Model = CanESM2; Emissions Scenario = historical, rcp85; Variable = altwsdiETCCDI
3. In Statistical Summary table, Time of Year selector includes all values, but only Annual is valid. All other selections show an error message at the bottom, but keep displaying the annual value.

The ToY selector should only show valid selections. General UI rule: Don't offer a user an invalid course of action.

[corviday]

Related enough it should probably be handled in the same PR: sometimes the initialization process selects an invalid Time of Year too.

[corviday]

Probably also the cause of this issue.

[rod-glover]

@corviday suggests cause: Stats table needs an algorithm parallel to the one for graphs that matches datasets on time resolution. ToY selector needs to (be fed data that):

1. Show all and only valid time resolutions.
2. Select a valid default.

Stats table needs first to be refactored into its own component first, to give this logic a legitimate place to live.

Addressing this should fix all 3 of these issues.