GetDotNetInstallScript has no retry behavior, fails on network flakiness

• Is this issue blocking (no)
• Is this issue causing unreasonable pain (no)

Reported by @333fred : https://dev.azure.com/dnceng/public/_build/results?buildId=503683&view=logs&jobId=1d3b3092-ebea-54d1-0a97-42044640f186&j=1d3b3092-ebea-54d1-0a97-42044640f186&t=229ccf78-8103-517e-b52d-eda4bea77a29

https://github.com/dotnet/arcade/blob/master/eng/common/tools.ps1#L191

We need to add basic retry logic to this function:

function GetDotNetInstallScript([string] $dotnetRoot) {
  $installScript = Join-Path $dotnetRoot 'dotnet-install.ps1'
  if (!(Test-Path $installScript)) {
    Create-Directory $dotnetRoot
    $ProgressPreference = 'SilentlyContinue' # Don't display the console progress UI - it's a huge perf hit
    Invoke-WebRequest "https://dot.net/$dotnetInstallScriptVersion/dotnet-install.ps1" -OutFile $installScript
  }

[MattGal]

Fairly certain I have seen this fail on linux; I believe the reason being curl’s version of retry is not for all possible error scenarios.

[MattGal]

@vzarytovskii - please consider Jared’s feedback when adding this: (" Is there any way to have curl dump diagnostic data too?")