Update instructions to set up trace server

[hoangphamEclipse]

The current instructions to set up the trace server for the trace extension does not explicitly indicate steps that only apply to Linux users. In addition, the lack of clear instructions for manually downloading and setting up the trace server makes it difficult for developers, who uses other OS, to run the trace server. This commit improves the documentation by providing clear instructions for developers on how to set up the server either by (1) using yarn, (2) downloading the server manually, or (3) building server manually. This will help contributors speed up their installation process, and reduce support effort.

[hoangphamEclipse]

@bhufmann Just letting you know that this PR is updated.