Sessions - changes view improvements (#305294)

* Only load the changes from last turn when needed

* Update action rendering

* Update title actions/context when switching sessions

* Add progress indicator

---------

Co-authored-by: Raymond Zhao <7199958+rzhao271@users.noreply.github.com>

src/vs/sessions/contrib/changes/browser/media/changesView.css

@@ -18,6 +18,11 @@
 	overflow: hidden;
 }
 
+/* Progress bar */
+.changes-view-body .chat-editing-session-container .changes-progress {
+	position: relative;
+}
+
 /* Welcome/Empty state */
 .changes-view-body .changes-welcome {
 	display: flex;
@@ -168,6 +173,7 @@
 	padding: 4px 8px;
 	font-size: 16px !important;
 }
+
 .changes-view-body .chat-editing-session-actions .monaco-button {
 	width: fit-content;
 	overflow: hidden;
@@ -260,6 +266,7 @@
 .changes-view-body .chat-editing-session-list .changes-decoration-badge.deleted {
 	color: var(--vscode-gitDecoration-deletedResourceForeground);
 }
+
 /* Line counts in list items */
 .changes-view-body .chat-editing-session-list .working-set-line-counts {
 	margin: 0 6px;