Ignite 3 Checkstyle improvement

[Ivan Zlenko]

Hi Ignite community!
I want to slightly improve our code style checks by introducing a new rule
which will disallow more than 1 empty line.
It should improve readability and consistency of our code base.
I've prepared a patch for this:
https://github.com/apache/ignite-3/pull/6367 and
if nobody opposes it I would like to merge it into Ignite 3.
Sincerely yours,
Ivan Zlenko.