Dynamic resizing of arrays

[Wodann]

Currently, arrays in Mun do not support dynamic resizing in Mun code, as we don't have the ability to call functions like push and resize. To support this, we need to implement:

• Ability to call member functions in the compiler backend
• Ability to specify generic function implementation for arrays (initial solution will inject this in the backend)

Depends on

• impl blocks for struct functions #503 (backend support)