Website: generate HTML chart+table with EJS

The generate-benchmark-html Python script creates an .html file based on
a .template.html file. The generated .html file is checked into the
repository, meaning that it needs to be manually synchronized with the
source .json benchmark data.

Rewrite the generate-benchmark-html Python script in JavaScript and use
the generation code from an EJS template. The website build process
(`yarn build`) will generate an index.html file from the .json benchmark
data and the index.ejs.html template.

The generated code for /benchmarks/index.html should be functionally
unchanged by this commit.

Author: strager

benchmark/benchmark-lsp/generate-benchmark-html

@@ -7,11 +7,3 @@ This directory contains benchmark results for display on the website.
     $ # Run the benchmarks:
     $ cd benchmark/benchmark-lsp/
     $ stack run -- -m glob "*/open-wait-close/express-router.js" --json ../../website/benchmarks/open-wait-close-express-router-js.json --time-limit 20
-    $ cd ../../
-
-    $ # Generate index.html:
-    $ python3 ./benchmark/benchmark-lsp/generate-benchmark-html website/benchmarks/index.template.html website/benchmarks/index.html
-
-    $ # Reformat HTML code:
-    $ cd website/
-    $ yarn fmt