tests/net_inet: Move tests which don't require full Internet to net_hosted.

The idea is that these tests can be run with just a test server running
on a test host, with device under test connecting to it, instead of
requiring Internet connection for testing.

Such setup is however WIP, and some tests in net_hosted/ are so far
written to connect to Internet, as there're not test server written
yet. This is expected to evolve over time.

tests/net_hosted/README

+This directory contains network tests which require just "peer to peer"
+network connection between test host and device under test, instead of
+full Internet connection.
+
+Note that setup for these tests and tests themselves are WIP, and may
+not yet fully correspond to the functional specification above.
+
+So far, these tests are not run as part of the main testsuite and need
+to be run seperately (from the main test/ directory):
+
+    ./run-tests net_hosted/*.py

tests/net_inet/README

-This direcctory contains network tests which require Internet connection.
+This directory contains network tests which require Internet connection.
 Note that these tests are not run as part of the main testsuite and need
 to be run seperately (from the main test/ directory):