Iowa and Mississippi omit farm rent, and New Mexico modified gross income omits partnership and farm income #10062

Found while reviewing state income lists for #10060, which adds estate_income to these lists and leaves the gaps below alone.

Iowa (2021 and 2022) and Mississippi: farm rent

Both states take the whole federal Schedule E amount:

• IA 1040 line 10: "Report the income or loss from federal Schedule E." (https://revenue.iowa.gov/media/2721/download?inline#page=19)
• Mississippi Form 80-105 line 41: "Enter the income or loss from activities reported on Federal Schedule E on this line." (https://www.dor.ms.gov/sites/default/files/tax-forms/individual/80100251%202.pdf#page=11)

gov.states.ia.tax.income.gross_income.sources and gov.states.ms.tax.income.income_sources include rental_income, partnership_s_corp_income and now estate_income, but not farm_rent_income (Form 4835). #9794 made the same fix for Arkansas on the ground that Form 4835 rent is reported on Schedule E; confirm that against the federal Schedule E instructions and add farm_rent_income to both lists.

New Mexico modified gross income: partnership and farm income

NMSA 1978 § 7-2-2(L) defines modified gross income as "all income ... undiminished by losses and from whatever source, including: ... (2) net profit from business; ... (13) distributive share of partnership income".

gov.states.nm.tax.income.modified_gross_income has self_employment_income and sstb_self_employment_income but neither partnership_s_corp_income nor farm_operations_income. Modified gross income gates the low-income comprehensive tax rebate, the property tax rebate and the child day care credit, so a household with partnership or farm income looks poorer than it is. The formula floors each source at zero, which matches 3.3.1.10 NMAC.

Each fix needs a YAML case with hand-computed values and, per the Axiom parity rule, a line in TheAxiomFoundation/rulespec-us#1633, #1634 or #1636.