feat(project): add the projects datasource

[Gnoale]

Example terraform

locals {
  public_key = "ssh-xxxx"
}

resource "scaleway_iam_ssh_key" "test" {
  name       = "main"
  public_key = local.public_key
  count      = length(data.scaleway_account_projects.test.projects)
  project_id = data.scaleway_account_projects.test.projects[count.index].id
}

fixes #3078