Add help link to .NET SDK install prompt

[gregg-miskelly]

This adds a Help link to the .NET SDK install prompt to help users troubleshoot problems with locating dotnet.

The help page to review: https://github.com/OmniSharp/omnisharp-vscode/wiki/Troubleshooting:-'The-.NET-Core-SDK-cannot-be-located.'-errors

This fixes #3507

[WardenGnaw]

Found the restart button but it still is failing with:

Failed to fetch https://packages.microsoft.com/ubuntu/16.04/prod/dists/xenial/main/binary-amd64/Packages Writing more data than expected (622228 > 606754)

Must be a cache error and might just need to wait a bit.

[gregg-miskelly]

The CI failure is from: dotnet/core#4122

[gregg-miskelly]

@WardenGnaw can you hit the restart button? The apt get issue is supposed to be fixed now.

[JoeRobich]

I hit the restart button for you.

[gregg-miskelly]

@JoeRobich Thanks. Can you poke it again (or just force it through) one flaky test...

[codecov]

Codecov Report

Merging #3508 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master   #3508   +/-   ##
======================================
  Coverage    89.8%   89.8%           
======================================
  Files          59      59           
  Lines        1589    1589           
  Branches       89      89           
======================================
  Hits         1427    1427           
  Misses        151     151           
  Partials       11      11

Flag	Coverage Δ
#integration	100% <ø> (ø)	⬆️
#unit	89.8% <ø> (ø)	⬆️

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[Gerhard-Piette]

DO NOT USE Ubuntu.
Not even the Binary file from https://dotnet.microsoft.com/download/dotnet/5.0 works because the dotnet executable is not recognized on Ubuntu. I guess it is related to dotnet-sdk on snap on Ubuntu.

I have no problems using the .net5 RC1 on Fedora 33 beta.

Download the dotnet-sdk SDK manually.
I have downloaded the Binaries from https://dotnet.microsoft.com/download/dotnet/5.0
No package manager.

Start VSCode with a script file with this content:
export PATH=$PATH:/YYY/
/home/XXX/Downloads/VSCode/code-insiders

where you have to adapt XXX and YYY to your case.
YYY is the folder where you have stored the SDK.

DO NOT USE Ubuntu snap.
Someone working on snap dotnet-sdk must have introduced an automatic "dotnet" alias that is listed but can not be removed with the "sudo snap unalias dotnet" command because Error: "cannot find manual alias "dotnet" in any snap".
Unfortunately the people working on omnisharp do not care about this problem.

From my console:

xxx:~$ dotnet

Usage: dotnet [options]
Usage: dotnet [path-to-application]

Options:
-h|--help Display help.
--info Display .NET information.
--list-sdks Display the installed SDKs.
--list-runtimes Display the installed runtimes.

path-to-application:
The path to an application .dll file to execute.
xxx:$ snap aliases
Befehl Alias Anmerkungen
dotnet-sdk.dotnet dotnet -
xxx:$ sudo snap unalias dotnet
Fehler: cannot find manual alias "dotnet" in any snap

Previously:

I made this post already here and here.

On Ubuntu 20.04.1, the problem is the snap alias. Do not install it.

Instead do this:

sudo snap install dotnet-sdk --channel=5.0/beta --classic

DO NOT install the alias because it makes Omnisharp not find the SDK.
sudo snap alias dotnet-sdk.dotnet dotnet

It can be removed with:
sudo snap unalias dotnet

Start VSCode with a script file with this content:
export PATH=$PATH:/snap/dotnet-sdk/current/
/home/XXX/Downloads/VSCode/code-insiders

You have to adapt the second line, that starts VSCode insiders, to your case.