Energy usage measurements on best-case low-footprint site prototype

[thibaudcolas]

Depends on #534, #535, #536. Once we have measurements of the "as-is" site, we can make the same measurements on a "best-case" version of the website.

• We use the "as-is" as the baseline (no changes)
• We use "best-case" as the upper bound of what we could realistically achieve with the most drastic optimizations
• The range between helps us understand what is the best-case improvement we could make.

For example, if loading the site takes 0.04Wh of CPU power "as-is", and the "best case" is 0.02Wh, we know we can achieve at most 50% reduction in relative terms, or 0.02Wh of reduction in absolute terms.

Tasks

• Re-run Firefox CPU measurements on best-case site created in Set up best-case local website copy for experimentation #536
• Re-run transfer size measurements on best-case site created in Set up best-case local website copy for experimentation #536
• Export in machine-readable format