[Reimbursements] Make it more obvious that approving an expense is different from approving the report.

> [!NOTE]
> This issue has been assigned to @ByteAtATime

Managers of orgs often approval all individual expenses and forget to approve the reimbursement report as a whole.

## Fix

Replace the approve all expenses button with a button to approve the entire report.
Automatically approve the report when approving the last expense.