chore: deprecating account and project user

[ivan-savciuc]

About this change—what it does

Deprecating account teams and team member resources alongside project users, as discussed internally.

⚠️ The deprecation message does not contain a particular resource as the recommended replacement because we do not expect a 1-to-1 transition from account to organization, and not all organization-related functionality will be transferred to the Terraform provider due to an internal investigation.

[Serpentiel]

the message mentions "Organization User Groups" but doesn't provide a clear reference to it—this can confuse users; we should offer a more explicit path or documentation for users to follow when transitioning

to ensure a smooth transition for users, might we consider delaying this PR until we have a clear replacement or at least a documented alternative?

[ivan-savciuc]

the message mentions "Organization User Groups" but doesn't provide a clear reference to it—this can confuse users; we should offer a more explicit path or documentation for users to follow when transitioning

to ensure a smooth transition for users, might we consider delaying this PR until we have a clear replacement or at least a documented alternative?

@Serpentiel I explicitly mentioned this in the PR description

please read the PR description

[Serpentiel]

lgtm