FINERACT-2318: add LoanApplicationModifiedBusinessEvent & LoanWithdrawnByApplicantBusinessEvent

[JebronLames32]

Description

At the moment, events are emitted for Loan application creation, approval, rejection, charge adjustment, and many others, but does not emit an event when

1. a loan application in SUBMITTED_AND_PENDING_APPROVAL state is modified (e.g. loan amount or term updated)
2. a loan application is withdrawn by the applicant before approval. An external service can get to know that the application has been withdrawn through the LoanStatusChangedBusinessEvent but unlike approval, rejection, and creation, it does not have an event of its own

Checklist

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[adamsaghy]

@JebronLames32 Please rebase your PR to resolve the conflicts!

[JebronLames32]

@adamsaghy rebased!

[JebronLames32]

@adamsaghy request you to please review so I can avoid merge conflicts again. Thanks!