Validate AZURE_EXISTING_AIPROJECT_RESOURCE_ID and assign roles if necessary to gain access

Our requirements:

o Validate AZURE_EXISTING_AIPROJECT_RESOURCE_ID has proper format.
o Validate users have permission to assign roles to the RG of the project
o Need a solution to assign OpenAI User role to the RG of existing AI Project. Currently bicep fails to assign roles to an existing RG if the role already assigned if the prior assignment job name different from bicep.

Currently validated the format in a hook. If invalid, it exits with code 1, which causes an unknown error in azd. Permission check and role assignment can be done by az commands in hook.