Test loops

[trdavidt]

Add two tests:

1. check if a number is prime (function call, while loop, early return, more complicated branching)
2. find nth Fibonacci number (loop over an array).

Made changes to src/instruction.rs and src/translate.rs to support additional branch instructions and bit shift left.

[Samir-Rashid]

Great work. Thanks for adding all of this. I have some minor comments for you to fix before merging.

Only improvement for future PRs is to pull main before committing or rebasing so there aren't useless merge commits in the history.

[Samir-Rashid]

Addressed comments. Looks good now.