Redis Sort out mess with module commands' proc and getkeys_proc

currently, all module commands' proc point to the same function (RedisModuleCommandDispatcher) yet the actual command pointer is stored in getkeys_proc (which points to a RedisModuleCommand, which is a structure, not a function)

this whole scheme is a bit off and causes a great deal of confusion

Comment From: oranagra

i think it's ok that the proc is RedisModuleCommandDispatcher. but i think the module pointer should be stored in a proper field named module. i'm curious to know how many changes this fix will introduce.