Add getkeys-api to the DAGRUN command

[lantiga]

Addresses #434

[codecov]

Codecov Report

Merging #435 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #435   +/-   ##
=======================================
  Coverage   72.97%   72.97%           
=======================================
  Files          21       21           
  Lines        4504     4504           
=======================================
  Hits         3287     3287           
  Misses       1217     1217           

Impacted Files	Coverage Δ
src/redisai.c	78.79% <100.00%> (ø)

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[gkorland]

@lantiga I don't see where you call RedisModule_KeyAtPos and RedisModule_IsKeysPositionRequest

[lantiga]

You are right, my bad.
After further consideration though, we will need to defer this to after merging #424: in the new DAGRUN PR we factor out parsing all kets before blocking, which makes it a lot easier to implement the missing functions.

[lantiga]

In scope: #160 #161

[filipecosta90]

closing this one in favor of #438 , which already addresses this issue for MODELRUN, DAGRUN, and SCRIPTRUN