Dgraph v22.0.0-RC1.20221003 release candidate

[myo (Mehdi Yousfi)]

Hi @Mentioum,

Thanks for your suggestion.

Here are my main requests for DQL:

• pick random node, without duplicates (Pick random node - #19 by hardik)
• more math functions, like basic abs (Feature request: math function abs)
• filtering a variable for aggregation not working (Filtering before aggregation not working)
• cond with strings (Math cond on strings)
• cond supporting empty variables (Expected a value variable in cond but missing: Accepting empty variables)