[ruby] Don't send 'for loop' feedback on 'accumulate' exercise

[kotp]

From exercism/exercism.io#3338 requested by @armchairlinguist regarding the Ruby Accumulate exercise specifically.

Feed back from Rikki was:

Rubyists tend to prefer methods over for loops.

[kytrinyx]

I'm pretty sure we could make that happen.

We would need to hard-code rules in the ruby analyzer, presumably to filter out certain smells after getting the results back from the static analysis service, and before shuffling the results to grab a response.

[kytrinyx]

I changed my mind about making the ruby analyzer handle this. The ruby analyzer should be agnostic to which exercise it is, and just spit out a set of potential violations.

Rikki should be able to filter out certain rules for certain exercises.

[kytrinyx]

We've added support for passing the slug to the analyzer, so we can now update the code to ignore the for loop feedback for accumulate.

My suggestion would be to exclude the smell here if it's the accumulate exercise: https://github.com/exercism/rikki/blob/master/analysis/ruby/ruby.go#L74-L79