Tetris: Speedrun Timer

Adds a timer for NES speedruns where the goal is to complete 100 lines. Future additions may include the ability to choose between several categories, as well as a "qualifying" mode for NES Tetris tournaments. Some technical notes:

- The timer assumes a 60fps console, when in actuality most NES's run at ~60.098fps. This is not really a massive issue because it takes over 10 minutes for the error to exceed a second, but the correct time can be found by multiplying the raw time by 60/60.098.
- Pausing is disabled.
- Until the run's completion, the displayed time is actually a frame longer than the actual elapsed time. For some reason the timer stops incrementing the frame before 100 lines is visibly reached, so this discrepancy is compensated for here.

Database match: Tetris (USA)
Database: No-Intro: Nintendo Entertainment System (v. 20210216-231042)
File SHA-1: 77747840541BFC62A28A5957692A98C550BD6B2B
File CRC32: 6D72C53A
ROM SHA-1: FD9079CB5E8479EB06D93C2AE5175BFCE871746A
ROM CRC32: 1394F57E