Remove deprecated netsocket methods

[kivaisan]

Summary of changes

Remove deprecated methods from netsocket

Impact of changes

Deprecated methods in netsocket (since Mbed OS 5.1) are removed.

Migration actions required

InternetSocket::attach -> Use Socket::sigio
TCPSocket(S *stack) -> Use default TCPSocket constructor and call open separately
UDPSocket(S *stack) -> Use default UDPSocket constructor and call open separately

Documentation

n/a

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Pull request type

[] Patch update (Bug fix / Target update / Docs update / Test update / Refactor)
[] Feature update (New feature / Functionality change / New API)
[X] Major update (Breaking change E.g. Return code change / API behaviour change)

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Test results

[] No Tests required for this change (E.g docs only update)
[X] Covered by existing mbed-os tests (Greentea or Unittest)
[] Tests / results supplied as part of this PR

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Reviewers

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[ciarmcom]

@kivaisan, thank you for your changes.
@ARMmbed/mbed-os-ipcore @ARMmbed/mbed-os-maintainers please review.

[0xc0170]

Deprecated methods in netsocket (since Mbed OS 5.11) are removed.

I edited Impact of changes to define details what is being deprecated.

[0xc0170]

CI started

[mbed-ci]

Test run: SUCCESS

Summary: 6 of 6 test jobs passed
Build number : 1
Build artifacts