Add `FORMULA()` SOQL Function

[cwarden]

Calculate Values in a SOQL WHERE Clause (Pilot)

Update parser and soql engine to support FORMULA() function in SOQL queries.

The syntax is:

SELECT fields FROM object WHERE FORMULA('field1 op field2') comparisonOp literalValue

The op can be + or -.

For field1 and field2 the supported types are DOUBLE, INTEGER, DATETIME, DATE, CURRENCY. field1 and field2 must be of the same type.

https://ideas.salesforce.com/s/idea/a0B8W00000GdWc8UAF/use-formulas-in-soql-where-clause

[cwarden]

Need to wait until May 10 when Summer '26 preview scratch orgs can be created since this is a pilot feature.