bitbake: bitbake: hashserv: Add hash equivalence reference server

Implements a reference implementation of the hash equivalence server.
This server has minimal dependencies (and no dependencies outside of the
standard Python library), and implements the minimum required to be a
conforming hash equivalence server.

[YOCTO #13030]

(Bitbake rev: 1bb2ad0b44b94ee04870bf3f7dac4e663bed6e4d)

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/bin/bitbake-selftest

@@ -22,6 +22,7 @@ sys.path.insert(0, os.path.join(os.path.dirname(os.path.dirname(__file__)), 'lib
 import unittest
 try:
     import bb
+    import hashserv
     import layerindexlib
 except RuntimeError as exc:
     sys.exit(str(exc))
@@ -35,6 +36,7 @@ tests = ["bb.tests.codeparser",
          "bb.tests.parse",
          "bb.tests.persist_data",
          "bb.tests.utils",
+         "hashserv.tests",
          "layerindexlib.tests.layerindexobj",
          "layerindexlib.tests.restapi",
          "layerindexlib.tests.cooker"]