JIT: Fix for :shrink scheduling

[hikettei]

TODO

• [ ] !concatenate !split for JIT=1
  • [ ] Use read-type-relay instead of Aref
  • [ ] only used to store :storage-id and is scalar or not
  • [ ] Remove Aref (no offsets/spaces are used)
  • [ ] Rename Aref -> DECLARE-VAR
  • [ ] this should come with refactoring
• [ ] Get MHA Scheduling working (and fuse xq xk xv)
• [ ] :shrink fusion
• [ ] ConvND = 1 Kernels

[hikettei]

Somehow remove this pattern from the graph ...

val_2 <- AREF
val_2 <- AREF
val_3 <- add(val_2, val_2)