Add chruby config to hide RUBY_ENGINE when "ruby"

Previously, the chruby segment looks like this for standard and
non-standard ruby implementations respectively:

```
Ruby ruby 3.1.2
Ruby truffleruby 3.0.3
```

While displaying the RUBY_ENGINE is helpful for non-standard
implementations, showing it for "ruby" results in "Ruby ruby" which
feels redundant.

This commit adds a new configuration option to disable showing the
RUBY_ENGINE when it is "ruby". Other values for RUBY_ENGINE will always
display as before:

```
Ruby 3.1.2
Ruby truffleruby 3.0.3
```

This also makes the formatting more similar to the asdf segment:

```
Ruby 3.1.2
Ruby truffleruby-22.3.0
```

0 files changed, 0 insertions, 0 deletions