Add ultra ui command

[xoofx]

ultra should provide the firefox-profiler via the command ultra ui by starting a local webserver.

It could also open for a fork/customization of the firefox-profiler for .NET (when we can't upstream or when upstreaming takes ages)

[xoofx]

For instance, I would like to support showing files with lines when clicking on a stack frame by connecting to local files on the disk. I could use a URL scheme to allow this with the UI.

[jsjtxietian]

Hi I have a commit does the basic server thing here : jsjtxietian@03e04a9

it will automaticly start a web server and open the firefox profiler page with json loaded. It can be closed when pass no-open. If it feels right I can make a pr based on this commit.

For instance, I would like to support showing files with lines when clicking on a stack frame by connecting to local files on the disk. I could use a URL scheme to allow this with the UI.

Me too, it would be useful but it requires some changes.