Add support for contiguous memory allocation and pointers

[GlowingScrewdriver]

The goal is to have support for multi-dimensional arrays and pointers.

• memory is allocated on the stack
• alloc and load are implemented as value instructions
• store instruction takes two arguments and returns nothing
• More notes will be added as progress is made

The following tests are ported and passing from BRIL:

• ptr_call -- pointer as a function parameter
• ptr_ret -- pointer as a return value
• access
• access_many
• access_ptr -- multi-dimensional pointers
• alloc
• fib -- computing the Fibonacci sequence

The following tests will not be ported:

• alloc_large, alloc_many -- repeated allocation and freeing. Not applicable since we don't have the concept of freeing.

[GlowingScrewdriver]

Ik I forgot to apply Black :grimacing: Will do for the next commit

[GlowingScrewdriver]

Added test: mem_id Also implemented the id instruction (which is actually a core BRIL instruction)

[chsasank]

Do run black

[GlowingScrewdriver]

Included two new tests that aren't from BRIL: arr_sum and transpose. These are two programs that actually make use of the arrays to solve problems.

[chsasank]

This is a great PR. Clean code, lot of tests! Great job!