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/settings/CalibreSettingsActivity.h

@@ -8,8 +8,8 @@
 #include "activities/ActivityWithSubactivity.h"
 
 /**
- * Submenu for Calibre settings.
- * Shows Calibre Web URL and Calibre Wireless Device options.
+ * Submenu for OPDS Browser settings.
+ * Shows OPDS Server URL and HTTP authentication options.
  */
 class CalibreSettingsActivity final : public ActivityWithSubactivity {
  public: