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

@@ -0,0 +1,11 @@
+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_hosted/accept_nonblock.py

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+# test that socket.accept() on a non-blocking socket raises EAGAIN
+
+try:
+    import usocket as socket
+except:
+    import socket
+
+s = socket.socket()
+s.bind(socket.getaddrinfo('127.0.0.1', 8123)[0][-1])
+s.setblocking(False)
+s.listen(1)
+try:
+    s.accept()
+except OSError as er:
+    print(er.args[0] == 11) # 11 is EAGAIN
+s.close()

tests/net_hosted/accept_nonblock.py.exp

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+True

tests/net_hosted/accept_timeout.py

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+# test that socket.accept() on a socket with timeout raises ETIMEDOUT
+
+try:
+    import usocket as socket
+except:
+    import socket
+
+try:
+    socket.socket.settimeout
+except AttributeError:
+    print('SKIP')
+    raise SystemExit
+
+s = socket.socket()
+s.bind(socket.getaddrinfo('127.0.0.1', 8123)[0][-1])
+s.settimeout(1)
+s.listen(1)
+try:
+    s.accept()
+except OSError as er:
+    print(er.args[0] in (110, 'timed out')) # 110 is ETIMEDOUT; CPython uses a string
+s.close()

tests/net_hosted/accept_timeout.py.exp

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+True

tests/net_hosted/connect_nonblock.py

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+# test that socket.connect() on a non-blocking socket raises EINPROGRESS
+
+try:
+    import usocket as socket
+except:
+    import socket
+
+s = socket.socket()
+s.setblocking(False)
+try:
+    s.connect(socket.getaddrinfo('micropython.org', 80)[0][-1])
+except OSError as er:
+    print(er.args[0] == 115) # 115 is EINPROGRESS
+s.close()

tests/net_hosted/connect_nonblock.py.exp

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+True