Limited emoji support for InkHUD (#7176)

* Cram a few emoji into AdafruitGFX fonts
Values which would normally be assigned to unprintable control characters

* Another sneaky string which may contain UTF-8 chars

* Document emoji

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Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

src/graphics/niche/InkHUD/Applet.cpp

@@ -353,10 +353,9 @@ std::string InkHUD::Applet::parseShortName(meshtastic_NodeInfoLite *node)
 // Determine if all characters of a string are printable using the current font
 bool InkHUD::Applet::isPrintable(std::string text)
 {
-    // Scan for DEL (0x7F), which is the value assigned by AppletFont::applyEncoding if a unicode character is not handled
-    // Todo: move this to from DEL to SUB, once the fonts have been changed for this
+    // Scan for SUB (0x1A), which is the value assigned by AppletFont::applyEncoding if a unicode character is not handled
     for (char &c : text) {
-        if (c == '\x7F')
+        if (c == '\x1A')
             return false;
     }