Add printing_merge_request_link_enabled attribute to projects

As mentioned on #782, the field is available on GitLab but still not
possible to use on terraform

Reference:
- https://github.com/gitlabhq/terraform-provider-gitlab/issues/782

docs/data-sources/project.md

@@ -69,6 +69,8 @@ The following attributes are exported:
 
 * `remove_source_branch_after_merge` - Enable `Delete source branch` option by default for all new merge requests
 
+* `printing_merge_request_link_enabled` - Show link to create/view merge request when pushing from the command line.
+
 * `packages_enabled` - Enable packages repository for the project.
 
 * `push_rules` Push rules for the project (documented below).

docs/resources/project.md

@@ -133,6 +133,8 @@ The following additional attributes are exported:
 
 * `remove_source_branch_after_merge` - Enable `Delete source branch` option by default for all new merge requests.
 
+* `printing_merge_request_link_enabled` - Show link to create/view merge request when pushing from the command line.
+
 ## Nested Blocks
 
 ### push_rules

examples/gitlab-managed-state/main.tf

@@ -41,6 +41,7 @@ resource "gitlab_project" "api" {
   only_allow_merge_if_all_discussions_are_resolved = true
   only_allow_merge_if_pipeline_succeeds            = true
   remove_source_branch_after_merge                 = true
+  printing_merge_request_link_enabled              = true
 
   container_registry_enabled = false
   lfs_enabled                = false

gitlab/data_source_gitlab_project.go

@@ -99,6 +99,10 @@ func dataSourceGitlabProject() *schema.Resource {
 				Type:     schema.TypeBool,
 				Computed: true,
 			},
+			"printing_merge_request_link_enabled": {
+				Type:     schema.TypeBool,
+				Computed: true,
+			},
 			// lintignore: S031 // TODO: Resolve this tfproviderlint issue
 			"push_rules": {
 				Type:     schema.TypeList,
@@ -189,6 +193,7 @@ func dataSourceGitlabProjectRead(d *schema.ResourceData, meta interface{}) error
 	d.Set("runners_token", found.RunnersToken)
 	d.Set("archived", found.Archived)
 	d.Set("remove_source_branch_after_merge", found.RemoveSourceBranchAfterMerge)
+	d.Set("printing_merge_request_link_enabled", found.PrintingMergeRequestLinkEnabled)
 
 	log.Printf("[DEBUG] Reading Gitlab project %q push rules", d.Id())
 

gitlab/resource_gitlab_project.go

@@ -687,6 +687,10 @@ func resourceGitlabProjectUpdate(d *schema.ResourceData, meta interface{}) error
 		options.RemoveSourceBranchAfterMerge = gitlab.Bool(d.Get("remove_source_branch_after_merge").(bool))
 	}
 
+	if d.HasChange("printing_merge_request_link_enabled") {
+		options.RemoveSourceBranchAfterMerge = gitlab.Bool(d.Get("printing_merge_request_link_enabled").(bool))
+	}
+
 	if d.HasChange("packages_enabled") {
 		options.PackagesEnabled = gitlab.Bool(d.Get("packages_enabled").(bool))
 	}