Update .NET Core Lambda deployment task to work with global tools

[stevejroberts]

The .NET Core Lambda Deployment task does not currently work with the new global dotnet CLI tools unless the user has pre-installed them on the build host and they are on path.

We need to update the task to auto-install the global tools and invoke from their install location (in case the current process has not picked up the change to PATH).

[melih154]

For anyone having the same problem, here is the hack we come up with.

steps:
- script: 'dotnet tool install -g Amazon.Lambda.Tools'
  displayName: 'Install Amazon.Lambda.Tools'
- powershell: |
   Copy-Item "$env:USERPROFILE\.dotnet\tools\dotnet-lambda.exe" -Destination "C:\Program Files\dotnet"
   Copy-Item "$env:USERPROFILE\.dotnet\tools\.store" -Destination "C:\Program Files\dotnet" -Recurse
  displayName: 'Copy Amazon.Lambda.Tools'

Ps. Only works with Windows agent. Re Linux agent, will try to use (Get-Command dotnet).Path to get the path,

[hunterwerlla]

This is added as part of the 1.5 release