port daily->weekly utilities to epiprocess

[dsweber2]

[dsweber2]

Several are in here: https://github.com/cmu-delphi/exploration-tooling/blob/main/R/aux_data_utils.R @nmdefries

[dshemetov]

Nat: downstream of date utilities stuff.
Logan: related version type not equal to time_value.

[dsweber2]

cmu-delphi/epiprocess#528 old version of this idea