Igniters, I've added the "All async methods should have async suffix" rule to Ignite 3 style guide [1]
Reason: - when both sync and async variants exist, async suffix is required for the code to compile, because the only difference is return value type - when only async variant exists, we want to have consistent naming anyway Most of the code base already follows this rule, let's have it in writing. Let me know if there are any objections. [1] https://cwiki.apache.org/confluence/display/IGNITE/Java+Code+Style+Guide#JavaCodeStyleGuide-4.1Allasyncmethodsshouldhaveasyncsuffix
