Implement year-specific satellite imagery

[mneveroff]

It should be possible to use historical satellite imagery from Landsat 7/8 and/or Sentinel-2 to produce timelapse-like satellite layers for each of the dataset years from 2012 to 2022, making the comparison and reporting accuracy much better.

Concerns:

• It's important to double-check the NFI and other data source effective dates so that we don't assign a satellite image to a year that doesn't guarantee reporting "before" satellite imagery date
• The above is especially important when de-clouding the image by sampling different days
• It's important to select a time of year that's representative of canopy cover to be useful, i.e. not winter in the UK to make sure broadleaves aren't barren

Inspiration / research:

• https://gisgeography.com/free-historical-imagery-viewers/
• https://livingatlas.arcgis.com/wayback/#active=6678&mapCenter=-2.16291%2C50.72385%2C15
• https://duckduckgo.com/?q=using+google+earth+timelapse+layer+by+layer&t=brave&ia=web
• https://blog.research.google/2019/06/an-inside-look-at-google-earth-timelapse.html