Add discontinued incomes section

[ToddWebDev]

Did you change site-wide styles, platform utilities or other infrastructure?

• No
• Yes

Summary

Import Discontinued Incomes - Section 11 into the Income & Asset Statement form (21P-0969)

Issue

• Section XI: Discontinued or irregular income va.gov-team#86454

Associated Pull Request(s)

n/a

How to run in local environment

1. Check out this branch locally
2. Run vets-website and vets-api
3. In your local environment, set the income_and_assets_form_enabled flipper to 'enabled' at http://localhost:3000/flipper/features/income_and_assets_form_enabled
4. Go to http://localhost:3001/pension/apply-for-veteran-pension-form-21p-527ez/ in your browser

How to verify

1. Go to chapter 10 - Assets previously not reported (/unreported-assets-summary)
2. Verify that an unreported asset can be added, edited, and deleted
3. Verify that unreported assets are displayed on the 'Review' page

What areas of the site does it impact?

Income & Asset Statement Application

Screenshots

Desktop

Summary Page

No Incomes	Incomes

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Item Pages

Relationship	Type

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Quality Assurance & Testing

• New unit tests (if applicable)
• New E2E tests added (if applicable)
• Existing unit tests and integration tests are passing
• Existing E2E tests are passing
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs
• Linting warnings have been addressed
• Documentation has been updated (link to documentation *if necessary)
• Screenshot style, layout and content matches the design references
• Accessibility testing has been performed

Error Handling

• Browser console contains no warnings or errors.
• Events are being sent to the appropriate logging solution
• Feature/bug has a monitor built into Datadog or Grafana (if applicable)

Authentication

• Did you login to a local build and verify all authenticated routes work as expected with a test user

Requested Feedback

(OPTIONAL) What should the reviewers know in addition to the above. Is there anything specific you wish the reviewer to assist with. Do you have any concerns with this PR, why?