Enable `conda (de)activate` in PowerShell

conda_from_pwsh.ps1

function conda($cmd) {
  # ↓ Change me
  $scripts_root = "C:\tools\Anaconda3\Scripts"
  function Add-ScriptsRootIfNeeded($exe) {
    $ret = if (Get-Command $exe -ErrorAction Ignore) {
      $exe
    }
    else {
      Join-Path $scripts_root $exe
    }
    return $ret
  }
  switch -Exact ($cmd) {
    "activate" {
      & (Add-ScriptsRootIfNeeded "activate.ps1") @args
      break
    }
    "deactivate" {
      & (Add-ScriptsRootIfNeeded "deactivate.ps1") @args
      break
    }
    default {
      $all_args = if ($null -ne $cmd) { @($cmd) + $args } else { @() }
      & (Add-ScriptsRootIfNeeded "conda.exe") @all_args
      break
    }
  }
}