Support type-checking on spreadsheet fields (part 3—last part)

[jfdoming]

Please see this link to view the diff of this PR excluding parts 1 and 2.

This PR (along with the previous ones, see PRs for parts 1 and 2) adds stricter types to the "spreadsheet" utilities used in the app. See part 1 for more context. This PR adds types for the report-budget spreadsheet and removes the any types.

Please see this link for a collapsed version of all the PRs.