Validate new config files before updating them.

Before replacing an existing config file with a new one the updater should use the AutoTxConfigTest tool to ensure the new one is valid.

We have to consider two different situations:

1. Only the config file will be updated.

• Easy, simply use the existing AutoTxConfigTest to check the new file. Test if the checker works on UNC paths. [CONFIRMED] * [ ] Otherwise copy the new file locally before and test it there.

1. Config and service binaries will be updated.

• This is more difficult. Probably the most robust approach would be to copy the new binaries (including AutoTxConfigTest) into a temporary local folder along with the new configuration and run it there. Otherwise we could try to run everything via UNC paths without copying [CONFIRMED TO WORK].

Related info:

• Environment.Exit Method (Int32)
• Difference between $? and $LastExitCode in PowerShell