Capture all components of SPM resources in spm_unit_net_income

[MaxGhenis]

We're currently missing some like medical and childcare expenses

https://www.census.gov/content/dam/Census/library/publications/2021/demo/p60-275.pdf#page=22

We can start by ensuring we can reproduce SPM resources in the raw ASEC from individual components there

[MaxGhenis]

I confirmed in this notebook that Census defines SPM resources as these items:

Item Name	Type	PolicyEngine variable	Description
SPM_TOTVAL	Addition	spm_unit_market_income	Total cash income
SPM_SNAPSUB	Addition	snap	SNAP
SPM_SCHLUNCH	Addition	free_school_meals + reduced_price_school_meals	School lunch subsidy
SPM_WICVAL	Addition	wic	WIC
SPM_CAPHOUSESUB	Addition	spm_unit_capped_housing_subsidy	Capped housing subsidy
SPM_ENGVAL	Addition	N/A	Energy subsidy
SPM_BBSUBVAL	Addition	spm_unit_broadband_subsidy	Broadband/Internet Subsidy
SPM_FEDTAX	Subtraction	income_tax	Federal tax after credits
SPM_STTAX	Subtraction	state_income_tax	State tax after credits
SPM_FICA	Subtraction	payroll_tax	FICA contributions
SPM_CHILDSUPPD	Subtraction	child_support_expense	Child support paid
SPM_MEDXPNS	Subtraction	medical_out_of_pocket_expenses	Medical Out-of-Pocket (MOOP) and Medicare Part B subsidy
SPM_CAPWKCCXPNS	Subtraction	N/A	Capped work and child care expenses

Not all of these are currently in spm_unit_net_income: we need to add variables for energy subsidy and capped work and child care expenses, and then apply those and subtract child support and medical expenses, while adding broadband subsidies.

Given these differ from our standard household net income measure, I wonder if we should distinguish this concept as spm_unit_spm_resources.