chore(null): address straightforward null check errors for src/common/components

[madalynrose]

Details

This PR is the first part of an effort to add the entire src/common/components/ directory to tsconfig.strictNullChecks.json. This addresses the straightforward null check fixes needed to add that directory.

The one slightly tricky change here removes fixInstructionProcessor from props for RulesWithInstances, as it is already present in deps.

Motivation

Works towards #2869

Context

A followup PR will address the one outstanding strict null failure, makingcardSelectionMessageCreator optional for all result sections.

Pull request checklist

• Addresses an existing issue: Codebase should use strict null checks #2869
• Ran yarn null:autoadd
• Ran yarn fastpass
• Added/updated relevant unit test(s) (and ran yarn test)
• Verified code coverage for the changes made. Check coverage report at: <rootDir>/test-results/unit/coverage
• PR title AND final merge commit title both start with a semantic tag (fix:, chore:, feat(feature-name):, refactor:). See CONTRIBUTING.md.
• [N/A] (UI changes only) Added screenshots/GIFs to description above
• [N/A] (UI changes only) Verified usability with NVDA/JAWS

[dbjorge]

LGTM, thanks Madalyn!