Add fast option to Black

Black takes arguments. How do we pipe these in? For example, I'd like to send Black the `--fast` command-line arguments.

https://github.com/diffplug/spotless/blob/224f8f96df3ad42cac81064a0461e6d4ee91dcaf/plugin-maven/src/main/java/com/diffplug/spotless/maven/python/Black.java#L25-L31

We can add a property to run it fast:

```
--fast / --safe By default, Black performs an AST safety
check after formatting your code. The --fast
flag turns off this check and the --safe
flag explicitly enables it. [default:
--safe]
```