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/CrossPointSettings.h

@@ -95,6 +95,8 @@ class CrossPointSettings {
   uint8_t screenMargin = 5;
   // OPDS browser settings
   char opdsServerUrl[128] = "";
+  char opdsUsername[64] = "";
+  char opdsPassword[64] = "";
   // Hide battery percentage
   uint8_t hideBatteryPercentage = HIDE_NEVER;
   // Long-press chapter skip on side buttons