raygun: Set a restriction to reactions

[dariusc93]

In the current implementations, reactions are unbound in itself, allowing for any length of text for the reactions, however leaving it unbound internally can lead to increase in memory if a larger reaction is set. Adding a check to restrict the length would help, but the question would be to what specific length since some implementations may use unicode, while others might use shortcode/cldr and translate that on the frontend.

For the time being, I believe, 128 characters will work, and what could be done is that we can have this adjustable in the configuration on a frontend-by-frontend basis, however restricting it so that it will only receive reaction events when those lengths is less than or equal to the configured amount, while anything more it would get rejected.