Move sqlcipher targets into GRDBCipher

Proof of concept related to:
groue#480

Not working:

- Various failing tests with getting back `SQLITE_ERROR` instead of
  `SQLITE_MISUSE`.  Not sure about this..

- Doesn't work with new Xcode build system.  Since the
  `sqlcipher-amalgamation` target builds `sqlite3.c`, I don't think the
  new build system knows about this, so it fails the build of
  the `sqlcipher-ios` target immediately say that "sqlite3.c is missing"

  Might need to use a custom run script build phase that explicitly sets
  the outputs.

GRDB.xcworkspace/xcshareddata/WorkspaceSettings.xcsettings

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>BuildSystemType</key>
+	<string>Original</string>
+</dict>
+</plist>