[Master] Expense Agent - Added Automated Test For API Pages

[v-rohangarg20]

Fixes AB#637260

Summary

Adds comprehensive automated integration tests for all Expense Agent API pages, validating API exposure, data retrieval, field accuracy, and related-entity expansion.

Changes

• src/Apps/W1/ExpenseAgent/test/src/API/ExpenseAPIPagesTest.Codeunit.al: ~1,300 lines, 40+ test methods covering expense categories, subcategories, groups, expenses, itemizations, participants, rules, and posted reports.
• Verifies API entity exposure via VerifyRecordVisibleInApi().
• Validates $expand for related entities (expenseItemizations, expenseParticipants, expenseRuleViolations).
• Confirms service-enabled actions for creating expense users and initializing test data via ExpenseTestHandler.
• Verifies correct field values returned by API GET requests.

Type of change

• Test automation (no product behavior change)