This patches the connection instances generated for the winssh
communicator so when a command is executed it is always run
with powershell. This prevents inconsistencies with argument
handling based on what the default shell is set to on the remote
side.
Since powershell is the default, environment variable template
only needs to be set for powershell style. If the shell setting
is updated to `cmd`, the command will be properly prefixed.
Default shell has been updated to powershell, to prevent extraneous
wrapping where it's not required. The `#ready?` check has also been
updated to use a constant value, which is overridden within winssh
as a blank command is invalid.
This commit normalizes our Windows paths to use `/` instead of `\`.
These paths are compatible with both cmd and PowerShell, and are
required if the server-side shell is set to Bash.
The OpenSSH server executes all commands inside a default login shell
which cannot be controlled by the Vagrant configuration. So what ends up
getting executed on the server side looks something like this:
"c:\\program files\\git\\bin\\bash.exe" -c "C:\\Windows\\Temp\\vagrant-ssh20200130-41670-1w5nsjy.bat"
By flipping the direction of the directory slashes, we end up with:
"c:\\program files\\git\\bin\\bash.exe" -c "C:/Windows/Temp/vagrant-ssh20200130-43415-f1d5n2.bat"
This works whether the server-side shell is set to cmd, powershell, or
bash.
