Add comps and sales val indicators to desk review workbook

[jeancochrane]

This PR implements the two biggest changes to the desk review workbook outlined in #168, namely:

• Adding top 2 comps and their scores to the PIN Detail sheet, with a link out to a new Sales sheet with details for each comp
  • As part of this change, we also include a new "Overall comps score" column that averages all of the available comps for the parcel
• Adding outlier flags from sales validation to the top 2 recent sales in the PIN Detail sheet, and color coding the associated sale columns to grab the reader's attention in the case of a flagged sale

Connects #168. A follow-up PR will implement the remaining features outlined in that issue.

[jeancochrane]

This is ready for another look @dfsnow! Changes that still need to be made that I plan to do in a follow-up PR include:

• [ ] Neighborhood breakouts
• [ ] Adding column for number of units

Once this PR is merged, my plan is to shift my focus to testing individual weights for comps (https://github.com/ccao-data/model-res-avm/issues/193) and then come back to tackle these last two changes.