Address a few corner cases in install script

- Sometimes for a completely unknown reason, the powershell archive module can't be imported because it is blocked by execution policy - even though we're running up to date pwsh, in admin, with local file, and unrestricted execution policy. So I've added another case for extracting archives on Windows machines that uses tar.exe if it is present (on all win10 machines past 1703). Hopefully this bypasses the bug.

- used simpler icons for conhost hosted processes on windows
- made symlinking to AP optional and issued a warning about admin mode when it fails

build/download_ap.ps1

@@ -317,7 +317,14 @@ function Get-Asset($asset_url) {
                 throw "Failed extracting $downloaded_zip using unzip"
             }
         }
+        elseif (Get-Command unzip -CommandType Application -ErrorAction SilentlyContinue) {
+            tar --extract --xz --file $downloaded_zip --directory $Destination
+            if ($LASTEXITCODE -ne 0) {
+                throw "Failed extracting $downloaded_zip using tar"
+            }
+        }
         else {
+            # the archive module has given us lots of problems - we try to avoid it if possible
             Import-Module "Microsoft.PowerShell.Archive" -Force
             Microsoft.PowerShell.Archive\Expand-Archive -LiteralPath $downloaded_zip -DestinationPath $Destination -Force
 
@@ -531,7 +538,18 @@ $actions =  [ordered]@{
         } )
     }
     "Symlink alias for AP" = @{
-        "Install" = ({"Symlink $alias_path to $ap_path"}, { if($null -eq $alias_path) { return $null } New-Item -Type SymbolicLink -Force -Path $alias_path -Target $ap_path | Out-Null ; return  $true } )
+        "Install" = ({"Symlink $alias_path to $ap_path"}, {
+            if($null -eq $alias_path) { return $null }
+
+            try {
+                New-Item -Type SymbolicLink -Force -Path $alias_path -Target $ap_path | Out-Null ;
+            }
+            catch {
+                Write-Warning "Failed to symlink AP. Are you running with administrator privileges?"
+                $_ | Out-String | Write-Debug
+            }
+            return  $true
+        } )
         "Check" = ("$alias_path exists and points to $ap_path",  {
             return (Test-Path $alias_path) `
               -and ((Get-Item $alias_path).LinkType -eq 'SymbolicLink') `
@@ -550,6 +568,18 @@ $actions =  [ordered]@{
     }
 }
 
+$success_symbol = "✅"
+$skip_symbol = "➖"
+$fail_symbol = "❌"
+
+if ($IsWindows -and !$env:WT_SESSION) {
+    # we're on windows and not in Windows Terminal (but rather conhost.exe)
+    # conhost does not support emoji so change success indicators
+    $success_symbol = "+"
+    $skip_symbol = "~"
+    $fail_symbol = "!"
+}
+
 function Invoke-APInstallTask($current, $key) {
     if ($null -eq $current) {
         Write-Debug "${indent} no task for $key, skipped"
@@ -574,15 +604,15 @@ function Invoke-APInstallTask($current, $key) {
 
     switch ($result) {
         { $err } {
-             Write-Error "${indent}❌ [error] AP's installation has a problem: $message`n Error:$($err | Out-String)"
+             Write-Error "${indent}$fail_symbol [error] AP's installation has a problem: $message`n Error:$($err | Out-String)"
              exit 1
         }
         $false {
-             Write-Error "${indent}❌ [error] AP's installation has a problem: $message failed"
+             Write-Error "${indent}$fail_symbol [error] AP's installation has a problem: $message failed"
              exit 1
         }
-        $null { Write-Information "${indent}➖ [skipped] $message" }
-        $true { Write-Information "${indent}✅ [success] $message" }
+        $null { Write-Information "${indent}$skip_symbol [skipped] $message" }
+        $true { Write-Information "${indent}$success_symbol [success] $message" }
         default {
             throw "unexpected result: $result"
         }
@@ -634,15 +664,15 @@ function Write-Metadata() {
 switch -wildcard ($PsCmdlet.ParameterSetName) {
     "Install-*" {
         Invoke-APInstallTasks $actions "Install"
-        Write-Information "✅ Installed AP $installed_version"
+        Write-Information "$success_symbol Installed AP $installed_version"
      }
     "Check" {
         Invoke-APInstallTasks $actions "Check"
-        Write-Information "✅ Check complete for AP version $installed_version"
+        Write-Information "$success_symbol Check complete for AP version $installed_version"
     }
     "Uninstall" {
         Invoke-APInstallTasks $actions "Uninstall"
-        Write-Information "✅ Uninstalled AP"
+        Write-Information "$success_symbol Uninstalled AP"
     }
     default {
         Write-Output "No action selected, no action taken, exiting"