Extend diagnostics to handle tcpip diagnostics client option

[mdh1418]

In effort to enable diagnostics tests for mobile (specifically Android) in dotnet/runtime#60879, it was realized that some changes to Microsoft.Diagnostics.NETCore.Client are needed in order for the eventpipe runtime tests to work (bigevent, buffersize, eventsourceerror). More specifically, DiagnosticsClient needed to handle a TCPIP option. With most of the functionality brought up by @lateralusX previously, just a new transport type is needed for the tests to work (without the new transport type, exceptions are thrown because the API only expects two type of transports)

The expectation for the shared code between this repository and Dotnet/Runtime is that any modifications to src/tests/tracing/eventpipe/common/Microsoft.Diagnostics.NETCore.Client in Dotnet/Runtime must first be made here in Dotnet/Diagnostics and once passed, will then be downstreamed to Dotnet/Runtime.

This pr accomplishes the following:

1. Introduces Dotnet/Runtime-specific PropertyGroup and ItemGroup into Microsoft.Diagnostics.NETCore.Client.csproj to define DIAGNOSTICS_RUNTIME constant, ignore compiler warnings, and compile the source code.
2. Adds a new transport type TcpSocket for TCP/IP case yet wraps it under a DIAGNOSTICS_RUNTIME #if directive to limit modifications to this repository. Also extends IpcTransport.Connect with TcpClient to handle the TCP/IP transport.
3. Adds a new file AssemblyInfo.cs completely wrapped under the above mentioned directive in order for internals to be visible on dotnet/runtime/src/tests/tracing/eventpipe/common/.
4. Wraps IpcSocket.AcceptAsync and IpcSocket.ConnectAsync in a #if !NET6_0 preprocessor directive because .NET 6 implements the methods directly and throws on Dotnet/Runtime
5. Adds a TCP/IP comment for the expectation of IpcEndpointConfig.Address

[noahfalk]

I think this is fine in principle - suggested a few changes and agreed with @josalem that the constructor should be internal.

[mdh1418]

@noahfalk @hoyosjs @josalem This PR captures the entirety of expected changes to Microsoft.Diagnostics.NETCore.Client source code in order to get Dotnet/Runtime diagnostics tests working on Android. It'll be easier to see just the changes than on dotnet/runtime#64358

[noahfalk]

LGTM modulo a few minor comments inline

[noahfalk]

Do we need to define NET_6 here, or does that happen somewhere else?

[hoyosjs]

NET_6 should be defined iff compiling against net6.0+ TFMs.

[mdh1418]

@noahfalk @hoyosjs I'll need help with the merge 😅 I dont have merge permissions in this repo

[hoyosjs]

FYI - this override will always be used at runtime given our compilation modes, regardless of the runtime version that gets used.