fix: several QoL updates for SD font's UI (#1965)

## Summary

* **What is the goal of this PR?**  
Improve the UI based on feedback from someone on discord

> Downloading ALL fonts feature.
> 1.1 Disable sleep when downloading, in my case went directly to sleep
just right after downloading.
> 1.2 It would be great to have and overall progress indicator as we
only have the indication of each font family
> 1.3 Any cancel or pause function might come in handy in case battery
is running out and then resume or retry with pending fonts

* **What changes are included?**  
- Now the UI can show overall progress across every file being
downloaded in the batch, not just progress inside the current family.
- Extended `HttpDownloader::downloadToFile()` to accept a cancel flag
and abort the download.
- Rendered a cancel button in the font download UI while a download is
in progress.
- `preventAutoSleep()` in `FontDownloadActivity.h` now returns true for
`state_ == COMPLETE` and `state_ == ERROR` in addition to
`LOADING_MANIFEST` and `DOWNLOADING`

## Additional Context

Not very satisfied with how `HttpDownloader.cpp` is right now, might try
to refactor it after v1.3.0

---

### AI Usage

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src/network/HttpDownloader.h

@@ -32,6 +32,6 @@ class HttpDownloader {
    * Download a file to the SD card with optional credentials.
    */
   static DownloadError downloadToFile(const std::string& url, const std::string& destPath,
-                                      ProgressCallback progress = nullptr, const std::string& username = "",
-                                      const std::string& password = "");
+                                      ProgressCallback progress = nullptr, bool* cancelFlag = nullptr,
+                                      const std::string& username = "", const std::string& password = "");
 };