git apply --check should give some indication that a patch applies cleanly

[Daniel Dromboski <dandromb@gmail.com>]

Hi folks,

The main purpose of `git apply --check` is to see if a patch can apply.

It's not intuitive to a user, just from the command name, that "no
output" means your patch can apply cleanly.

Furthermore, `git apply --check --verbose` only says that it is
checking the patch, ending with "..." which usually means "more info
to come"... But it doesn't print anything else. An example command and
output:

```
$ git apply --check --verbose [my-patch.patch]
Checking patch [path/to/file.ext]...
```

I'd like if there were some way for the command to confirm outright
that the patch applies, to save users the confusion.

Thanks.