fix(provider): register cost-centers, billing-usage, and enterprise-scim resources and data sources

All feature branch implementations were merged into master but their
resources and data sources were missing from provider.go, causing
'unused' linter errors and make build to fail.

Registers:
- github_enterprise_cost_center (resource + data source)
- github_enterprise_cost_center_organizations (resource)
- github_enterprise_cost_center_repositories (resource)
- github_enterprise_cost_center_users (resource)
- github_enterprise_cost_centers (data source)
- github_enterprise_billing_usage (data source)
- github_enterprise_billing_usage_summary (data source)
- github_enterprise_billing_premium_request_usage (data source)
- github_enterprise_scim_group (data source)
- github_enterprise_scim_groups (data source)
- github_enterprise_scim_user (data source)
- github_enterprise_scim_users (data source)

Author: vmvarela

github/provider.go

@@ -212,6 +212,10 @@ func Provider() *schema.Provider {
 			"github_user_gpg_key":                                                   resourceGithubUserGpgKey(),
 			"github_user_invitation_accepter":                                       resourceGithubUserInvitationAccepter(),
 			"github_user_ssh_key":                                                   resourceGithubUserSshKey(),
+			"github_enterprise_cost_center":                                         resourceGithubEnterpriseCostCenter(),
+			"github_enterprise_cost_center_organizations":                           resourceGithubEnterpriseCostCenterOrganizations(),
+			"github_enterprise_cost_center_repositories":                            resourceGithubEnterpriseCostCenterRepositories(),
+			"github_enterprise_cost_center_users":                                   resourceGithubEnterpriseCostCenterUsers(),
 			"github_enterprise_organization":                                        resourceGithubEnterpriseOrganization(),
 			"github_enterprise_team":                                                resourceGithubEnterpriseTeam(),
 			"github_enterprise_team_membership":                                     resourceGithubEnterpriseTeamMembership(),
@@ -301,6 +305,15 @@ func Provider() *schema.Provider {
 			"github_enterprise_teams":                                               dataSourceGithubEnterpriseTeams(),
 			"github_enterprise_team_membership":                                     dataSourceGithubEnterpriseTeamMembership(),
 			"github_enterprise_team_organizations":                                  dataSourceGithubEnterpriseTeamOrganizations(),
+			"github_enterprise_billing_usage":                                       dataSourceGithubEnterpriseBillingUsage(),
+			"github_enterprise_billing_usage_summary":                               dataSourceGithubEnterpriseBillingUsageSummary(),
+			"github_enterprise_billing_premium_request_usage":                       dataSourceGithubEnterpriseBillingPremiumRequestUsage(),
+			"github_enterprise_cost_center":                                         dataSourceGithubEnterpriseCostCenter(),
+			"github_enterprise_cost_centers":                                        dataSourceGithubEnterpriseCostCenters(),
+			"github_enterprise_scim_group":                                          dataSourceGithubEnterpriseSCIMGroup(),
+			"github_enterprise_scim_groups":                                         dataSourceGithubEnterpriseSCIMGroups(),
+			"github_enterprise_scim_user":                                           dataSourceGithubEnterpriseSCIMUser(),
+			"github_enterprise_scim_users":                                          dataSourceGithubEnterpriseSCIMUsers(),
 			"github_repository_environment_deployment_policies":                     dataSourceGithubRepositoryEnvironmentDeploymentPolicies(),
 		},
 	}