feat: Lyra Icons (#725)

/!\ This PR depends on
https://github.com/crosspoint-reader/crosspoint-reader/pull/732 being
merged first

Also requires the
https://github.com/open-x4-epaper/community-sdk/pull/18 PR

## Summary

Lyra theme icons on the home menu, in the file browser and on empty book
covers

![IMG_8023
Medium](https://github.com/user-attachments/assets/ba7c1407-94d2-4353-80ff-d5b800c6ac5b)
![IMG_8024
Medium](https://github.com/user-attachments/assets/edb59e13-b1c9-4c86-bef3-c61cc8134e64)
![IMG_7958
Medium](https://github.com/user-attachments/assets/d3079ce1-95f0-43f4-bbc7-1f747cc70203)
![IMG_8033
Medium](https://github.com/user-attachments/assets/f3e2e03b-0fa8-47b7-8717-c0b71361b7a8)


## Additional Context

- Added a function to the open-x4-sdk renderer to draw transparent
images
- Added a scripts/convert_icon.py script to convert svg/png icons into a
C array that can be directly imported into the project. Usage:
```bash
python ./scripts/convert_icon.py 'path/to/icon.png' cover 32 32
```
This will create a components/icons/cover.h file with a C array called
CoverIcon, of size 32x32px. Lyra uses icons from
https://lucide.dev/icons with a stroke width of 2px, that can be
downloaded with any desired size on the site.

> The file browser is noticeably slower with the addition of icons, and
using an image buffer like on the home page doesn't help very much. Any
suggestions to optimize this are welcome.

---

### AI Usage

While CrossPoint doesn't have restrictions on AI tools in contributing,
please be transparent about their usage as it
helps set the right context for reviewers.


Did you use AI tools to help write this code? _**PARTIALLY**_
The icon conversion python script was generated by Copilot as I am not a
python dev.

---------

Co-authored-by: Dave Allie <dave@daveallie.com>

src/components/themes/BaseTheme.h

@@ -61,6 +61,8 @@ struct ThemeMetrics {
   bool keyboardCenteredText;
 };
 
+enum UIIcon { Folder, Text, Image, Book, File, Recent, Settings, Transfer, Library, Wifi, Hotspot };
+
 // Default theme implementation (Classic Theme)
 // Additional themes can inherit from this and override methods as needed
 
@@ -111,7 +113,7 @@ class BaseTheme {
   virtual void drawList(const GfxRenderer& renderer, Rect rect, int itemCount, int selectedIndex,
                         const std::function<std::string(int index)>& rowTitle,
                         const std::function<std::string(int index)>& rowSubtitle = nullptr,
-                        const std::function<std::string(int index)>& rowIcon = nullptr,
+                        const std::function<UIIcon(int index)>& rowIcon = nullptr,
                         const std::function<std::string(int index)>& rowValue = nullptr,
                         bool highlightValue = false) const;
   virtual void drawHeader(const GfxRenderer& renderer, Rect rect, const char* title,
@@ -125,11 +127,11 @@ class BaseTheme {
                                    bool& bufferRestored, std::function<bool()> storeCoverBuffer) const;
   virtual void drawButtonMenu(GfxRenderer& renderer, Rect rect, int buttonCount, int selectedIndex,
                               const std::function<std::string(int index)>& buttonLabel,
-                              const std::function<std::string(int index)>& rowIcon) const;
+                              const std::function<UIIcon(int index)>& rowIcon) const;
   virtual Rect drawPopup(const GfxRenderer& renderer, const char* message) const;
   virtual void fillPopupProgress(const GfxRenderer& renderer, const Rect& layout, const int progress) const;
   virtual void drawReadingProgressBar(const GfxRenderer& renderer, const size_t bookProgress) const;
   virtual void drawHelpText(const GfxRenderer& renderer, Rect rect, const char* label) const;
   virtual void drawTextField(const GfxRenderer& renderer, Rect rect, const int textWidth) const;
   virtual void drawKeyboardKey(const GfxRenderer& renderer, Rect rect, const char* label, const bool isSelected) const;
-};
+};