Annotate System.Net.Security for nullable reference types

[eiriktsarpalis]

Contributes to #2339

I think I might have spotted a few bugs, please see my comments in the diff /cc @dotnet/ncl

[eiriktsarpalis]

Rebased on top of newly added System.Net.Primitives annotations

[eerhardt]

    public InvalidCredentialException(string message, System.Exception innerException) { }

string? message, System.Exception? innerException. Here and for string message overload above.

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Refers to: src/libraries/System.Net.Security/ref/System.Net.Security.cs:583 in cadecbf. [](commit_id = cadecbf680f43be03eb4fd7ca59df230ffe075ba, deletion_comment = False)

[eerhardt]

    public bool Contains(string searchServiceName) { throw null; }

From a quick look at the code, it appears that Contains(string searchServiceName) handles passing in null. Should this be string? searchServiceName?

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Refers to: src/libraries/System.Net.Security/ref/System.Net.Security.cs:617 in cadecbf. [](commit_id = cadecbf680f43be03eb4fd7ca59df230ffe075ba, deletion_comment = False)

[eiriktsarpalis]

Rebased on top of System.Net.Sockets annotations.

[eerhardt]

Assuming your questions to the library owners are resolved, this LGTM. Nice work.