Refactors Calibre Wireless Device & Calibre Library (#404)

Our esp32 consistently dropped the last few packets of the TCP transfer
in the old implementation. Only about 1/5 transfers would complete. I've
refactored that entire system into an actual Calibre Device Plugin that
basically uses the exact same system as the web server's file transfer
protocol. I kept them separate so that we don't muddy up the existing
file transfer stuff even if it's basically the same at the end of the
day I didn't want to limit our ability to change it later.

I've also added basic auth to OPDS and renamed that feature to OPDS
Browser to just disassociate it from Calibre.

---------

Co-authored-by: Arthur Tazhitdinov <lisnake@gmail.com>
Co-authored-by: Dave Allie <dave@daveallie.com>

src/activities/network/NetworkModeSelectionActivity.h

@@ -8,11 +8,12 @@
 #include "../Activity.h"
 
 // Enum for network mode selection
-enum class NetworkMode { JOIN_NETWORK, CREATE_HOTSPOT };
+enum class NetworkMode { JOIN_NETWORK, CONNECT_CALIBRE, CREATE_HOTSPOT };
 
 /**
  * NetworkModeSelectionActivity presents the user with a choice:
  * - "Join a Network" - Connect to an existing WiFi network (STA mode)
+ * - "Connect to Calibre" - Use Calibre wireless device transfers
  * - "Create Hotspot" - Create an Access Point that others can connect to (AP mode)
  *
  * The onModeSelected callback is called with the user's choice.