shell: Use a top-level React component

And rewrite much of the state handling to make it easier to
understand.

Specifically, the old Index and MachineIndex classes and their
complicated interactions have been replaced with a hopefully much more
straightforward ShellState class.

However, the existing React components such as CockpitHosts and TopNav
have not been significantly touched.

The API for launching the HostModal dialogs has been changed to make
it more suitable for a later rewrite with Dialogs.run() ala
pkg/lib/cockpit-connect-ssh.

files.js

@@ -28,7 +28,7 @@ const info = {
         "playground/remote.tsx",
 
         "selinux/selinux.js",
-        "shell/shell.js",
+        "shell/shell.jsx",
         "sosreport/sosreport.jsx",
         "static/login.js",
         "storaged/storaged.jsx",

pkg/shell/active-pages-modal.jsx

@@ -29,20 +29,18 @@ import { useInit } from "hooks";
 
 const _ = cockpit.gettext;
 
-export const ActivePagesDialog = ({ dialogResult, frames }) => {
+export const ActivePagesDialog = ({ dialogResult, state }) => {
     function get_pages() {
         const result = [];
-        for (const address in frames.iframes) {
-            for (const component in frames.iframes[address]) {
-                const iframe = frames.iframes[address][component];
+        for (const frame of Object.values(state.frames)) {
+            if (frame.url) {
+                const active = (frame == state.current_frame ||
+                                state.most_recent_path_for_host(frame.host) == frame.path);
                 result.push({
-                    frame: iframe,
-                    component,
-                    address,
-                    name: iframe.getAttribute("name"),
-                    active: iframe.getAttribute("data-active") === 'true',
-                    selected: iframe.getAttribute("data-active") === 'true',
-                    displayName: address === "localhost" ? "/" + component : address + ":/" + component
+                    frame,
+                    active,
+                    selected: active,
+                    displayName: frame.host === "localhost" ? "/" + frame.path : frame.host + ":/" + frame.path,
                 });
             }
         }
@@ -61,8 +59,9 @@ export const ActivePagesDialog = ({ dialogResult, frames }) => {
 
     function onRemove() {
         pages.forEach(element => {
-            if (element.selected)
-                frames.remove(element.host, element.component);
+            if (element.selected) {
+                state.remove_frame(element.frame.name);
+            }
         });
         dialogResult.resolve();
     }
@@ -80,8 +79,8 @@ export const ActivePagesDialog = ({ dialogResult, frames }) => {
         }];
         return ({
             props: {
-                key: page.name,
-                'data-row-id': page.name
+                key: page.frame.name,
+                'data-row-id': page.frame.name
             },
             columns,
             selected: page.selected,