Use script to install ARM version of .NET on ARM because of a UseDotNet bug

[MichelZ]

Looks like there's a bug in the UseDotNet Azure DevOps functionality and it installs x86 .NET on ARM:
microsoft/azure-pipelines-tasks#20300

Adding an install script to resolve this and install the proper version on ARM.
Also, the steps were added twice as prebuild and build. Removed one.

Here you can find the logs showing the x86 install:
https://dev.azure.com/sqlclientdrivers/public/_build/results?buildId=102454&view=logs&j=f62ec789-9893-5f91-3293-e8a10244adaa&t=83eb4f36-b8e6-57c5-1c44-e749ef0d4796

Starting: Initialize job
Agent name: 'ADO-CI-PUBLIC-ARM64-1ES-EUS-POOL 4'

Version 9.0.100 was not found in cache.
Getting URL to download .NET Core sdk version: 9.0.100.
Detecting OS platform to find correct download package for the OS.
C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -NoLogo -Sta -NoProfile -NonInteractive -ExecutionPolicy Unrestricted -Command "& 'D:\a\_work\_tasks\UseDotNet_b0ce7256-7898-45d3-9cb5-176b752bfea6\2.248.1\externals\get-os-platform.ps1'"
Primary:win-x86
Detected platform (Primary): win-x86
Downloading: https://download.visualstudio.microsoft.com/download/pr/d7af32e6-aaec-4fcd-aabe-0d927fa73a6d/80bbc4143ee82e40b8b4341795e92f4e/dotnet-sdk-9.0.100-win-x86.zip
Extracting downloaded package D:\a\_work\_temp\5c2afe6a-65ec-4414-ad1a-8368aeaecbe9.
Extracting archive

Note: This needs new packages added to the azure devops feed cache:
- microsoft.netcore.app.host.win-arm64 (I guess 8.0 & 9.0?)

##[error]tools\GenAPI\Microsoft.DotNet.GenAPI\Microsoft.DotNet.GenAPI.csproj(0,0): Error NU1301: Failed to retrieve information about 'Microsoft.NETCore.App.Host.win-arm64' from remote source 'https://sqlclientdrivers.pkgs.visualstudio.com/904996cc-6198-4d39-8540-eca72bdf0b7b/_packaging/e8fc87e8-fcf4-4bb0-a818-96a9fdd52378/nuget/v3/flat2/microsoft.netcore.app.host.win-arm64/index.json'.

[ErikEJ]

@MichelZ Maybe you can use the VS Code AzureDevops YAML validator 😄 ?

[MichelZ]

@MichelZ Maybe you can use the VS Code AzureDevops YAML validator 😄 ?

Today I learned.... Thanks!

[ErikEJ]

@MichelZ it just got too painful watching 😆