Add the ability to invite guest users from other tenants in Bicep

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Is your feature request related to a problem? Please describe.

I am a Cyber Engineer at a Microsoft partner MSSP which uses B2B collaboration to provide services to our clients. We invite our MSSP accounts (eg. analyst@mssp.com) to every client tenant (client.com). Every time we onboard a new client or hire a new analyst, we need to process 40+ guest invitations. This is a massive pain point for us as it can only be done using the API or SDK, which means we either need to do this manually, or create our own script using the SDK.

We already use Bicep extensively in our onboardings, but due to this lack of functionality we cannot integrate our guest accounts into our onboarding deployments. Not being able to use Bicep for managing guest accounts adds complexity by requiring manual, error-prone scripting with the MS Graph SDK. It eliminates the benefits of automation, idempotency, and ease of scaling, which Bicep provides. This results in more maintenance overhead and inconsistent deployment processes, undermining efficiency and reliability.

Describe the solution you'd like

We need the ability to declaratively invite guest users in a Bicep file. The ideal use case is for us to have a parameter with an array of accounts to invite, and adding/removing an account from the array will invite/delete the account(s) as appropriate.

We already have the Microsoft.Graph/users type. I see two possible solutions for adding this funcitonality:

1. Add a new resource type Microsoft.Graph/guestUsers which invites accounts from other tenants based on properties you give it
2. Add functionality to the Microsoft.Graph/users type which supports inviting guest accounts (eg. a property to set which defines whether the user is a tenant user or a guest to invite)

Additional context
API reference for guest user invitations - Link
B2B accounts documentation - Link
Microsoft.Graph/users type - Link