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.
Vagrant Core Plugins
These are plugins that ship with Vagrant. Vagrant core uses its own plugin system to power a lot of the core pieces that ship with Vagrant. Each plugin will have its own README which explains its specific role.