Precompute investment objective coefficients

[tsmbland]

Description

We currently calculate the coefficients (ObjectiveCoefficients, formerly CoefficientsMap) used in the investment algorithm multiple times (every time a new round of appraisal is performed), even though these values won't change.

A better approach is to calculate these upfront for all assets, store them, and pass individual ObjectiveCoefficientss to appraise_investment.

This won't be that impactful currently as the work to calculate the coefficients is small, but this will be more significant once we move the current code for calculating "reduced costs" over to the investment module

Close #885

[codecov]

Codecov Report

❌ Patch coverage is 82.92683% with 7 lines in your changes missing coverage. Please review.
✅ Project coverage is 85.41%. Comparing base (1cacfaf) to head (44038aa).
⚠️ Report is 8 commits behind head on main.

Files with missing lines	Patch %	Lines
src/simulation/investment/appraisal.rs	60.00%	4 Missing ⚠️
...rc/simulation/investment/appraisal/coefficients.rs	87.50%	3 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #888      +/-   ##
==========================================
+ Coverage   85.37%   85.41%   +0.04%     
==========================================
  Files          50       50              
  Lines        5319     5335      +16     
  Branches     5319     5335      +16     
==========================================
+ Hits         4541     4557      +16     
  Misses        559      559              
  Partials      219      219              

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[dalonsoa]

LGTM

[alexdewar]

LGTM too!

[alexdewar]

Do you need the type hint?

Suggested change

	let mut best_assets: Vec<AssetRef> = Vec::new();
	let mut best_assets = Vec::new();

[dalonsoa]

Not sure what the linters say, but sometimes, even though type hints might not be necessary for the program to compile, they are really useful for people reading the code.

[tsmbland]

Correct that the type annotation isn't required here.

I'm in two minds about this (and giving non-mandatory type annotations in general). On the one hand, not giving them means trimmer code that's easier to change, and if you're using the rust-analyzer plugin in vscode then it gives you these annotations anyway. On the other hand, you are quite reliant on rust-analyzer for readability, which doesn't help when looking at diffs on GitHub

[tsmbland]

I'm going to merge this as it is, but looking into it I think the idiomatic approach here is to not give the type hint