Avoid proxy issues for localhost only communication

[jasonmreding]

Description

This PR attempts to avoid grpc connection issues due to http proxies when communicating over loopback addresses. If we detect the target address for a gRPC channel is the localhost or equivalent, then we explicitly disable sending traffic through the proxy.

Implementation

• Added a git submuodule for asio which is what boost is based on. I attempted to use boost directly, but I couldn't figure out how to get headers only build to work in a reasonable way so I fell back to this solution which I found to be simpler.
• Updated cmake files to add new include directories for the headers which are being used from asio
• Updated LabVIEWgRPCClient::Connect to set GRPC_ARG_ENABLE_HTTP_PROXY to false if the target address is detected to be a loopback address.

Testing

I didn't see much in the way of an automated regression test framework so I didn't create any automated tests as part of this change. I manually tested that the following addresses worked and used the expected proxy settings:

• localhost
• localhost:42000
• 127.0.0.1
• 127.0.0.1:42000
• [::1]
• [::1]:42000
• http://localhost:42000
• foo

[j-medland]

Could the user just specify a local env variable to specify if the proxy should be ignored for localhost etc?

https://github.com/grpc/grpc/blob/591d56e1300b6d11948e1b821efac785a295989c/doc/environment_variables.md

[jasonmreding]

Could the user just specify a local env variable to specify if the proxy should be ignored for localhost etc?

https://github.com/grpc/grpc/blob/591d56e1300b6d11948e1b821efac785a295989c/doc/environment_variables.md

Yes, that is an option and is what we have been telling customers to avoid these issues. However, the errors you get when this is a problem aren't very helpful, and a lot of time is wasted via support channels before getting to the bottom of what is wrong.

[jasonmreding]

@yash-ni @ni-sujain It looks like you have the most recently submitted PRs to the repo. Can you help me find someone to review this PR and/or give me write access to the repo so I can see who approving reviewers are?

[ni-sujain]

@yash-ni @ni-sujain It looks like you have the most recently submitted PRs to the repo. Can you help me find someone to review this PR and/or give me write access to the repo so I can see who approving reviewers are?

I have given you access. Thanks