[Master]-Bug 648538: Add mileage setup to Expense Agent wizard

[v-rohangarg20]

Fixes AB#648538

Adds mileage configuration to the Expense Agent setup wizard and warns users when they close Mileage Rate Setup without configuring any mileage rates.

Changes are limited to:

• Expense Agent setup wizard mileage configuration link
• Mileage Rate Setup empty-configuration confirmation

AL build completed successfully.

[github-actions]

$\textbf{🟡\ Medium\ Severity\ —\ Agent}$

The new OnQueryClosePage trigger on page 7128 "Mileage Rate Setup" prompts "No mileage rates have been configured. The standard mileage rate will be used. Do you want to continue?" every time the page is closed with an empty table. This page has UsageCategory = Lists, so it is reachable directly from the Lists menu/search, not only from the Expense Agent Setup Wizard drill-down added in this PR. A user who opens the list independently (e.g., just to check whether rates exist) and closes it without adding a rate will see a setup-wizard-flavored confirmation that is confusing outside the wizard flow, and answering No leaves the page open with no clear indication of what action is expected. Consider moving this confirmation into the wizard's own close/validation flow, or scoping it so it only prompts when the page was opened modally from the wizard.

_{👍 useful · ❤️ especially valuable · 👎 wrong - reply with why · AL review agent v1.36.6}