relocate applypatch; add type system and new functions to edify

- Move applypatch to this package (from build).

- Add a rudimentary type system to edify:  instead of just returning a
  char*, functions now return a Value*, which is a struct that can
  carry different types of value (currently just STRING and BLOB).
  Convert all functions to this new scheme.

- Change the one-argument form of package_extract_file to return a
  Value of the new BLOB type.

- Add read_file() to load a local file and return a blob, and
  sha1_check() to test a blob (or string) against a set of possible
  sha1s.  read_file() uses the file-loading code from applypatch so it
  can read MTD partitions as well.

This is the start of better integration between applypatch and the
rest of edify.

b/2361316 - VZW Issue PP628: Continuous reset to Droid logo:
            framework-res.apk update failed (CR LIBtt59130)

Change-Id: Ibd038074749a4d515de1f115c498c6c589ee91e5
22 files changed