Rewrite score calculation in Rust

[nicoburns]

Score recalc is pretty slow currently. Slow enough that I left it and came back to it several times and it still wasn't done. We should consider rewriting it in Rust for better performance. Such an implementation could:

• Use streaming parsing for the JSON (and LZMA decompression) using a custom serde Deserialize implementation, avoiding allocating huge arrays of test results. This could be done both for top-level tests and sub-tests.
• Avoid allocating test name strings entirely by matching directly against the values in the raw file (which will never include escaped characters).

[mukilan]

I agree, rewriting in Rust makes sense. Originally we were planning to have the dashboard show the scores for just 1 year, with a fresh graph for each year like the interop dashboard, but now that we have a single graph, there is a lot of data to process.

Another option is to truncate and archive data beyond a cutoff date (which is what I do when testing changes locally).

[mukilan]

Also, at some point we'll be dropping the data for Layout 2013.