libsysprof-gtk: add SysprofSession

This is meant to become our toplevel object controlling an analysis
session. We need it to know about any filters in place such as time
selections.

Callgraph needs to be updated to use this as well.

src/libsysprof-gtk/sysprof-session.h

@@ -0,0 +1,41 @@
+/* sysprof-session.h
+ *
+ * Copyright 2023 Christian Hergert <chergert@redhat.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#pragma once
+
+#include <gtk/gtk.h>
+
+#include <sysprof-analyze.h>
+
+G_BEGIN_DECLS
+
+#define SYSPROF_TYPE_SESSION (sysprof_session_get_type())
+
+SYSPROF_AVAILABLE_IN_ALL
+G_DECLARE_FINAL_TYPE (SysprofSession, sysprof_session, SYSPROF, SESSION, GObject)
+
+SYSPROF_AVAILABLE_IN_ALL
+SysprofSession  *sysprof_session_new          (SysprofDocument *document);
+SYSPROF_AVAILABLE_IN_ALL
+SysprofDocument *sysprof_session_get_document (SysprofSession  *self);
+SYSPROF_AVAILABLE_IN_ALL
+GtkFilter       *sysprof_session_get_filter   (SysprofSession  *self);
+
+G_END_DECLS