Provisioning: Add common shared folder

Common shared folder includes scripts of files which are common for all
operating system families. Changes under shared folder will trigger
provisioning for all platforms

Change-Id: I0789f87b76876d5f92673fe2f0e72d770e5f5ea4
Task-number: QTQAINFRA-1451
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@qt.io>
(cherry picked from commit dc5f851e78)

coin/provisioning/common/windows/set-network-test-server.ps1

@@ -35,7 +35,7 @@
 
 # This script will set the network test server IP in to hosts file
 
-$n = Get-Content "$PSScriptRoot\network_test_server_ip.txt"
+$n = Get-Content "$PSScriptRoot\..\shared\network_test_server_ip.txt"
 $n = $n.Split('=')
 New-Variable -Name $n[0] -Value $n[1]