feat: Storage Layout Overrides

[abdullathedruid]

This is my first contribution, so would be grateful for everyones time spent reviewing this PR
Targeting #2572

What I did

• Added flag --storage-layout-file to compiler which takes a list of storage layout files
• Added some primitive checks to ensure the user does not accidentally cause storage collision

How I did it

• Updated compile_code function to take an additional optional argument, storage_layout_overrides. If provided, this is used to custom data position for storage. If it is omitted, then the compiler functions as normally

How to verify it

• Test script added

Description for the changelog

Added the ability to override storage slots for variables

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[codecov-commenter]

Codecov Report

Merging #2593 (02b1b20) into master (fe74711) will decrease coverage by 0.02%.
The diff coverage is 83.33%.

@@            Coverage Diff             @@
##           master    #2593      +/-   ##
==========================================
- Coverage   86.29%   86.26%   -0.03%     
==========================================
  Files          90       90              
  Lines        9291     9351      +60     
  Branches     2354     2370      +16     
==========================================
+ Hits         8018     8067      +49     
- Misses        789      796       +7     
- Partials      484      488       +4     

Impacted Files	Coverage Δ
vyper/cli/vyper_compile.py	72.58% <28.57%> (-2.64%)	⬇️
vyper/semantics/validation/data_positions.py	90.90% <88.00%> (-4.22%)	⬇️
vyper/compiler/__init__.py	87.17% <100.00%> (+1.46%)	⬆️
vyper/compiler/phases.py	94.05% <100.00%> (+0.05%)	⬆️
vyper/exceptions.py	92.72% <100.00%> (+0.06%)	⬆️

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[charles-cooper]

Nice approach, I think your approach is basically pretty clean. I made some suggestions which should make it easier to follow. I think the main thing would be to refactor StorageCollision so it only has a single publicly facing method, reserve_slot_range(self, slot: int, n_slots: int). This makes its usage clearer since there is only "one way to use it". Then, the internal implementation could be slightly simpler if you use a set instead of a dict.

[charles-cooper]

Left a few comments, also I think in Python double underscores are usually used for dunder methods; for private methods please use single underscores. Shaping up nicely, thank you!