Add old_name property to Resource schema

See: https://github.com/spring-projects/sts4/issues/633

headless-services/concourse-language-server/src/main/java/org/springframework/ide/vscode/concourse/PipelineYmlSchema.java

@@ -238,6 +238,7 @@ public class PipelineYmlSchema implements YamlSchema {
 		addProp(t_resource, "tags", t_strings);
 		addProp(t_resource, "webhook_token", t_ne_string);
 		addProp(t_resource, "icon", t_ne_string);
+		addProp(t_resource, "old_name", t_ne_string);
 
 		AbstractType t_image_resource = f.ybean("ImageResource");
 		{

headless-services/concourse-language-server/src/main/resources/desc/Resource/old_name.md

@@ -0,0 +1,20 @@
+*Optional* The old name of the resource. If configured, the history of the old resource will be inherited to the new one. Once the pipeline is set, this field can be removed as the history has been transferred.
+
+This can be used to rename a resource without losing its history, like so:
+
+```
+resources:
+- name: new-name
+  old_name: current-name
+  type: git
+  source: uri: "https://github.com/vito/booklit"
+ ```
+ 
+After the pipeline is set, the resource was successfully renamed, so the `old_name` field can be removed from the resource:
+
+```
+resources:
+- name: new-name
+  type: git
+  source: uri: "https://github.com/vito/booklit"
+```

headless-services/concourse-language-server/src/test/java/org/springframework/ide/vscode/concourse/ConcourseEditorTest.java

@@ -1906,6 +1906,7 @@ public class ConcourseEditorTest {
 				"- name: s3-multi\n" +
 				"  type: docker-image\n" +
 				"  check_every: bad-duration\n" + 
+				"  old_name: was-renamed\n" +
 				"  privileged: is-priviliged\n" +
 				"  tags: tags-list\n" +
 				"  unique_version_history: is-unique-hist\n" +
@@ -1928,6 +1929,7 @@ public class ConcourseEditorTest {
 				"resources:\n" +
 				"- name: sts4\n" +
 				"  type: git\n" +
+				"  old_name: was-renamed\n" +
 				"  icon: foo\n" + 
 				"  check_every: 5m\n" +
 				"  webhook_token: bladayadayaaa\n" +
@@ -1937,6 +1939,7 @@ public class ConcourseEditorTest {
 
 		editor.assertHoverContains("name", "The name of the resource");
 		editor.assertHoverContains("type", "The type of the resource. Each worker advertises");
+		editor.assertHoverContains("old_name", "history of the old resource will be inherited");
 		editor.assertHoverContains("icon", "name of a [Material Design Icon]");
 		editor.assertHoverContains("source", 2, "The location of the resource");
 		editor.assertHoverContains("webhook_token", "web hooks can be sent to trigger an immediate *check* of the resource");
@@ -4024,6 +4027,7 @@ public class ConcourseEditorTest {
 				//For the 'exact' context:
 				"check_every",
 				"icon",
+				"old_name",
 				"tags",
 				"webhook_token",
 				//"name", exists