fix(storedcredentials): define target match array to avoid undefined reference error

[andrewazores]

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Fixes: cryostatio/cryostat#756

Description of the change:

When a CredentialsStored notification is emitted, use the contents of that notification to patch the client-side model of the stored Credentials objects. The original returned value from the API response does not contain the real value, so this workaround keeps the UI in sync and avoids a t.targets is undefined error.

Motivation for the change:

This change is helpful because users may want to copy the example for easier use...

How to manually test:

1. See [Bug] When creating a Credential, UI displays error with t.targets is undefined cryostat#756