add check when borrowing value that it's not a reference

Adds an additional check in borrow to make sure that the value being borrowed is not itself a reference

[X] Targeted PR against master branch
[X] Linked to Github issue with discussion and accepted design OR link to spec that describes this work
[X] Code follows the standards mentioned here
[X] Updated relevant documentation
[X] Re-reviewed Files changed in the Github PR explorer
[X] Added appropriate labels

onflow / cadence