New match type: ddrSongHash

[tranq88]

ddrSongHash is a 32-character hash used by the official DDR e-amusement website to identify a song.

I believe Tachi supported this match type in the past but I didn't look too much into it. Re-implementing this will allow users to use services that scrape DDR scores from e-amusement, such as 3icecream (however their timestamps can be unreliable; I'm working on my own tool as well).

I tried my best to figure it out without official documentation. If anything's missing, please advise!

[zkrising]

Needs some small fixes/justifications before I'm willing to merge, but otherwise looks good. Thank you.

[nyairobi]

It may be a good idea to mention it in the docs before we forget

• ddr-SP.md
• ddr-DP.md
• batch-manual/index.md
• match-types.md

There are leftover references to the previous ddrSongHash implementation, funnily enough

Tachi/docs/docs/codebase/batch-manual/index.md

Line 75 in dc15834

| `matchType` | "songTitle" \| "ddrSongHash" \| "tachiSongID" \| "bmsChartHash" \| "inGameID" \| "uscChartHash" | This determines how `identifier` will be used to match your scores' chart with Tachi's database of songs and charts. |

and

Tachi/docs/docs/codebase/batch-manual/index.md

Line 77 in dc15834

| `difficulty` (Conditional) | String | If `matchType` is "tachiSongID", "inGameID", "ddrSongHash" or "songTitle", this field must be present, and describe the difficulty of the chart this score is for. |