feat: set up geoserver for rainfall_forecast and population

[jannisvisser]

Describe your changes

AB#32769

• While writing up the documentation I realized setting up Geoserver is an integral part to already cover with setting up a country
• I did this with dummy data for now, but from Lesotho so that the bounding box is correct (population data from https://data.humdata.org/dataset/worldpop-population-density-for-lesotho)
• This is accompanied by additional changes in Add country doc on Wiki

Checklist before requesting a review

• I have performed a self-review of my code
• I have added tests wherever relevant
• I have made sure that all automated checks pass before requesting a review