🪲 Several Add cmdlets for Agent Identity Blueprints don't handle adding new values to multi-value properties

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• Make sure you can reproduce this issue using the latest released version of Microsoft.Entra or Microsoft.Entra.Beta.
• Please search the existing issues to see if there has been a similar issue filed.

Describe the bug

Several Add cmdlets for Agent Identity Blueprints don't handle adding new values to multi-value properties, nor do they handle replacing existing property values. This includes at least:

1. Add-EntraBetaInheritablePermissionsToAgentIdentityBlueprint
2. Add-EntraBetaScopeToAgentIdentityBlueprint

To Reproduce

Steps to reproduce the behavior:

1. Execute Invoke‑EntraBetaAgentIdInteractive or manually create an AIB and populate one or both of the above properties
2. Run the Add cmdlet
3. Error will be thrown stating a value for that property already exists

Expected behavior

Either A) automatically append the new value to the property, B) ask the user if they want to append/replace, or C) offer-append and/or -replace modifiers to allow the user to update the property after some values have already been added (without having to manually remove the existing values).

Debug Output

⚠ ATTENTION: Be sure to remove any sensitive information that may be in the logs.

Start by reproducing the failure with Add-EntraBetaInheritablePermissionsToAgentIdentityBlueprint and Add-EntraBetaScopeToAgentIdentityBlueprint after an Agent Identity Blueprint already has values. Inspect how these cmdlets update multi-value properties and clarify whether append, replace, prompting, or explicit modifiers is intended; done means adding or replacing values no longer fails when values already exist.