Optional telemetry gathering

[nickspoons]

This PR adds command-line flag -wt/--want-telemetry-info to request calling dotnet --info for telemetry purposes, and to otherwise not gather this information. Fetching this data slows OmniSharp-roslyn startup, and fails in certain circumstances (see #1844).

The essence of the PR is that the --want-telemetry-info flag is included in OmniSharpEnvironment, and when it is not set, the _dotNetCli service is not passed in to ProjectManager. This essentially undoes the effects of PR #1820, which is where the _dotNetCli service began being passed in to ProjectManager.

cc @filipw (commenter on #1844) and @JoeRobich (author of #1820) - does this look like the right fix? Would you rather we look at doing it a different way?

Note that this new flag is to opt-out of extra info being collected. We discussed opting-in in #1844 but that is more complicated as it involves changes on the VScode side, which I'm not familiar with. (This PR requires changes on the Vim side, (which I can make) - as well as any other editors which choose to opt out).

Edit: the -nt/--no-telemetry-info opt-out flags have now been changed to opt-in flags, -wt/--want-telemetry-info

Fixes #1844

[nickspoons]

There are failed tests but I can't see what the problem is - are these related to my code changes?

Edit: never mind, I force pushed and the tests passed.

[filipw]

thanks a lot

Note that this new flag is to opt-out of extra info being collected. We discussed opting-in in #1844 but that is more complicated as it involves changes on the VScode side, which I'm not familiar with. (This PR requires changes on the Vim side, (which I can make) - as well as any other editors which choose to opt out).

IMHO if we are adding the flag it should make the telemetry metadata opt-in. New OmniSharp versions have to be manually added to VS Code extension anyway, so during that PR it would just be a matter of adding the extra startup flag, I wouldn't see that as very invasive.

Not to mention that, since this is improving perf quite considerably, it is in-line with the overall philosophy of Omnisharp of having a lean core and features on top of it that need to be enabled.

I am sure @david-driscoll and @JoeRobich would agree

[nickspoons]

Thanks @filipw, in that case I'll change the flag to opt-in some time this weekend.

[nickspoons]

I have replaced the -nt/--no-telemetry-info opt-out flags with -wt/--want-telemetry-info opt-in flags

[nickspoons]

Any chance you could give this a review, @JoeRobich, since it looks like you're getting ready for a release?

[JoeRobich]

I am not against this change, but hope that reducing the requests for dotnet --info to once per workspace works as a solution. see #1857

[JoeRobich]

nit: I know names are hard and this isn't a blocker but maybe IncludeTelemetryInfo instead

[nickspoons]

I'm happy to make that change. What about the flag names? --include-telemetry-info and -it ?

[nickspoons]

I've just built #1857 and works well for me. I tried it in this repo and did a few restarts, it generally is loading all projects on my machine in 21-23 seconds. Comparing that (my local build) with v1.35.2 (from the github release) it seems very similar - maybe a second slower but my testing is not at all robust enough to confirm that - and it may also be due to me having debug symbols in my local build.

I will therefore close this PR in favour of #1857 - thanks very much @JoeRobich (and @filipw for the helpful feedback).