Fix expectation and use of SocketsConfig_t::pAlpnProtos

[dachalco]

Description

As detailed in #3516, the expectation and use of pAlpnProtos was that of a string, but it's propagated to lower layers as an array of strings instead. Incorrectly calculating the number of separate protocols as the demos set pAlpnProtos as a string, yet transport_secure_sockets.c#L267 assumes the number of separate protocols is the length of this string.

Checklist:

• [X] I have tested my changes. No regression in existing tests.
• [x] My code is Linted.

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[dachalco]

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[dachalco]

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[xuelix]

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[dachalco]

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[xuelix]

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[dachalco]

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[gmtt]

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