:sparkless: FEATURE: Add variables support

[LucaDillenburg]

Is your feature request related to a problem? Please describe.
I'm always frustrated when I have to remember the memory address of all the data I have stored in RAM.

Describe the solution you'd like
Create variables that point to a memory address so that we don't have to remember the address. The Assembler should also know and calculate to which address to point automatically.
Code example with variable support (just an example, not this syntax necessarily):

# variable declaration at the beginning of the file
declare var_name

add var_name
store var_name

Describe alternatives you've considered
Part of the problem could be solved by a memory address alias. However, then the programmer would have to calculate where would the variable be created.

Additional context
Add any other context or screenshots about the feature request here.