[libraries] Skip GetOpenSslVersion on Apple OS

[mdh1418]

This PR looks to extend the PlatformNotSupportedException for OpenSslVersion from OSX to OSX, iOS, and tvOS, as none of these Apple OS support OpenSsl.

To test changes, reverted #36928 to get an OpenSslVersion exception.
Ran the tests and obtained similar errors.

Ran the tests with changes from this PR and obtained errors such as

        <failure exception-type="System.PlatformNotSupportedException">
          <message><![CDATA[System.PlatformNotSupportedException : Operation is not supported on this platform.]]></message>
          <stack-trace><![CDATA[   at System.PlatformDetection.get_OpenSslVersion()
   at System.PlatformDetection.get_SupportsAlpn()
   at System.Net.Test.Common.GenericLoopbackOptions..ctor()
   at System.Net.Test.Common.LoopbackServer.Options..ctor()
   at System.Net.Test.Common.LoopbackServer..ctor(Options options)
   at System.Net.Test.Common.LoopbackServer.CreateServerAsync(Func`2 funcAsync, Options options)
   at System.Net.Http.Json.Functional.Tests.HttpContentJsonExtensionsTests.TestValidMediaTypes(String mediaType)
--- End of stack trace from previous location ---]]></stack-trace>
        </failure>
      </test>```
[PNSE.txt](https://github.com/dotnet/runtime/files/4752719/PNSE.txt)

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[akoeplinger]

instead of adding this to the ref (which will be done in #36704 and needs API review), please instead use RuntimeInformation.IsOSPlatform(OSPlatform.Create("IOS")) in the usages.

[mdh1418]

Should a follow up after #36704 be to change them back to RuntimeInformation.IsOSPlatform(OSPlatform.iOS) and RuntimeInformation.IsOSPlatform(OSPlatform.tvOS)?

[akoeplinger]

ideally yes, but it's just a cosmetic cleanup