feat: show boot process notifications for PDDB

This commit shows two notifications:
 1. as soon as the device boots, a notification greets the user and
 tells them everything is fine, the device is booting
 2. as soon as the user enters (or doesn't) enter the password, a
 notification tell the user Xous is loading and mounting PDDB

I spent too much time on this but I believe it's a nice UX improvement.

services/pddb/src/main.rs

@@ -394,7 +394,7 @@ use std::collections::{HashMap, BTreeSet};
 use std::io::ErrorKind;
 use core::fmt::Write;
 use std::sync::atomic::{AtomicBool, Ordering};
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 
 use locales::t;
 
@@ -490,6 +490,34 @@ fn wrapped_main() -> ! {
         }
     });
 
+    let hide_startingup_notif = Arc::new(Mutex::new(false));
+    let hide_startingup_notif_clone = hide_startingup_notif.clone();
+
+    std::thread::spawn(move || {
+        // For some weird reason spawning a dynamic notification without waiting 800ms in a separate thread 
+        // makes it impossible to read, because it gets covered by hundreds of those modal security lines (???).
+        // This thread waits on hide_startingup_notif to become true, then disimsses the dynamic notification that it created
+        // previously.
+        // To allow other threads to do work, yield to kernel every time the variable is read as false.
+
+        let xns = xous_names::XousNames::new().unwrap();
+        let modals = modals::Modals::new(&xns).expect("can't connect to Modals server");
+
+        std::thread::sleep(std::time::Duration::from_millis(1000));
+
+        modals.dynamic_notification(Some("Starting up..."), Some("Precursor is booting up, please wait.")).unwrap();
+
+        loop {
+            if *hide_startingup_notif_clone.lock().unwrap() {
+                modals.dynamic_notification_close().unwrap();
+                break;
+            }
+
+            xous::yield_slice();
+        };
+    });
+
+
     // OS-specific PDDB driver
     let mut pddb_os = PddbOs::new(Rc::clone(&entropy), pw_cid);
     // storage for the basis cache
@@ -656,6 +684,8 @@ fn wrapped_main() -> ! {
             //    - code = 2 -> mount failed, because too many PINs were retried. `count` is the number of retries.
             // If we need more nuance out of this routine, consider creating a custom public enum type to help marshall this.
             Opcode::TryMount => xous::msg_blocking_scalar_unpack!(msg, _, _, _, _, {
+                *hide_startingup_notif.lock().unwrap() = true;
+
                 if basis_cache.basis_count() > 0 {
                     xous::return_scalar2(msg.sender, 0, 0).expect("couldn't return scalar");
                 } else {
@@ -669,6 +699,8 @@ fn wrapped_main() -> ! {
                     } else {
                         match ensure_password(&modals, &mut pddb_os, pw_cid) {
                             PasswordState::Correct => {
+                                modals.dynamic_notification(Some("Starting up..."), Some("Mounting PDDB, please wait.")).unwrap();
+
                                 if try_mount_or_format(&modals, &mut pddb_os, &mut basis_cache, PasswordState::Correct, time_resetter) {
                                     is_mounted.store(true, Ordering::SeqCst);
                                     for requester in mount_notifications.drain(..) {
@@ -680,8 +712,12 @@ fn wrapped_main() -> ! {
                                 } else {
                                     xous::return_scalar2(msg.sender, 1, 0).expect("couldn't return scalar");
                                 }
+
+                                modals.dynamic_notification_close().unwrap();
                             },
                             PasswordState::Uninit => {
+                                modals.dynamic_notification(Some("Starting up..."), Some("Mounting PDDB, please wait.")).unwrap();
+
                                 if try_mount_or_format(&modals, &mut pddb_os, &mut basis_cache, PasswordState::Uninit, time_resetter) {
                                     for requester in mount_notifications.drain(..) {
                                         xous::return_scalar2(requester, 0, 0).expect("couldn't return scalar");
@@ -693,6 +729,8 @@ fn wrapped_main() -> ! {
                                 } else {
                                     xous::return_scalar2(msg.sender, 1, 0).expect("couldn't return scalar");
                                 }
+
+                                modals.dynamic_notification_close().unwrap();
                             },
                             PasswordState::ForcedAbort(failcount) => {
                                 xous::return_scalar2(msg.sender, 2,