Compare Inputs in Results HTML

Is there any way to configure `benchee` or `benchee_html` to compare the inputs on one graph?

I can do this with something like the following:

```
Benchee.run(
%{
"tx_benchmark 100" => fn -> TraditionalLedger.run_benchmark_file("./data/transactions_100.csv") end,
"tx_benchmark 1000" => fn -> TraditionalLedger.run_benchmark_file("./data/transactions_1000.csv") end,
"tx_benchmark 10000" => fn -> TraditionalLedger.run_benchmark_file("./data/transactions_10000.csv") end,
},
formatters: [
{Benchee.Formatters.Console, extended_statistics: true},
{Benchee.Formatters.HTML, file: "benchmarks/results.html"},
],
after_each: fn _input -> reset_database() end,
)
```

But doing it like the following "feels" better in terms of the code, but the HTML comparison charts will put these on separate pages:

```
Benchee.run(
%{
"tx_benchmark" => fn input -> TraditionalLedger.run_benchmark_file(input) end,
},
formatters: [
{Benchee.Formatters.Console, extended_statistics: true},
{Benchee.Formatters.HTML, file: "benchmarks/results.html"},
],
inputs: %{
"100" => "./data/transactions_100.csv",
"1_000" => "./data/transactions_1000.csv",
"10_000" => "./data/transactions_10000.csv",
},
after_each: fn _input -> reset_database() end,
)
```

And output the following:

But I think this may just be a personal preference, but I could see there a use case for comparing `inputs` against each other in this fashion for benchmarking performance for different applications.