rs: allow parsing proxies given as full URIs

[connor4312]

Rather than only host:port

For microsoft/vscode#201417

Changes proposed:

• HTTPS_PROXY may be given as a URI rather than just host:port. Doing so is rather extraneous since only the host and port are used, but handle parsing it anyway.

Other Tasks:

• If you updated the Go SDK did you update the PackageVersion in tunnels.go
• If you updated the TS SDK did you update the dependencies in package.json for connections and management to require a dependency that is > the current published version(Found using npm view @microsoft/dev-tunnels-contracts). This will fix issues where yarn will pull the old version of packages and will cause mismatched dependencies. See example PR