Support for Powershell Core (7+): `pwsh` as an alternative to `powershell`

[tadaskay]

Is your feature request related to a problem? Please describe. Some functionality on windows depends on powershell executable (Windows Powershell) being available in PATH. Ensuring that, however, is troublesome in some outdated systems, because Windows Powershell is only installable via WMF which itself has separate installers for particular Windows versions. This update is usually not needed, but judging from some user reports, some systems may have auto updates disabled and thus encounter this problem. A much easier way would be to install the new cross platform Powershell Core (7+) that has its standalone installer. We could add such dependency to the desktop installer. It installs a binary pwsh that can be used side by side with the legacy Windows Powershell. What's needed from node/supervisor side, is to support pwsh as well as the legacy powershell command.

Additional context Related reports: https://github.com/mysteriumnetwork/node/issues/4773 https://github.com/mysteriumnetwork/mysterium-vpn-desktop/issues/313 https://github.com/mysteriumnetwork/node/issues/4819