add tcp-p3 example and test

[rvolosatovs]

Adapt the tcp example to p3 using wasi-sockets API directly until wasi-libc/wasi-sdk/cpython are further along in p3 support

[rvolosatovs]

Interesting, the CI just broke a few minutes ago (https://github.com/bytecodealliance/componentize-py/actions/runs/22143392814/job/64013519262?pr=204)

/usr/bin/git submodule sync --recursive
/usr/bin/git -c protocol.version=2 submodule update --init --force --depth=1 --recursive
Submodule 'cpython' (https://github.com/dicej/cpython) registered for path 'cpython'
Cloning into '/home/runner/work/componentize-py/componentize-py/cpython'...
Error: fatal: could not read Username for 'https://github.com/': terminal prompts disabled
Error: fatal: expected flush after ref listing
Unable to fetch in submodule path 'cpython'; trying to directly fetch 0e13686da8bb881b059d35e23c32bcd2e6440099:
Error: fatal: could not read Username for 'https://github.com/': terminal prompts disabled
Error: fatal: Fetched in submodule path 'cpython', but it did not contain 0e13686da8bb881b059d35e23c32bcd2e6440099. Direct fetching of that commit failed.
Error: The process '/usr/bin/git' failed with exit code 128/usr/bin/git submodule sync --recursive
/usr/bin/git -c protocol.version=2 submodule update --init --force --depth=1 --recursive
Submodule 'cpython' (https://github.com/dicej/cpython) registered for path 'cpython'
Cloning into '/home/runner/work/componentize-py/componentize-py/cpython'...
Error: fatal: could not read Username for 'https://github.com/': terminal prompts disabled
Error: fatal: expected flush after ref listing
Unable to fetch in submodule path 'cpython'; trying to directly fetch 0e13686da8bb881b059d35e23c32bcd2e6440099:
Error: fatal: could not read Username for 'https://github.com/': terminal prompts disabled
Error: fatal: Fetched in submodule path 'cpython', but it did not contain 0e13686da8bb881b059d35e23c32bcd2e6440099. Direct fetching of that commit failed.
Error: The process '/usr/bin/git' failed with exit code 128

[dicej]

Thanks!