* use pwsh over powershell if installed (on windows) for default shell
* refactor blockcontroller.DoRunShellCommand into a "setup" and "manage" phase
* fix wshcmd-conn to also disconnect wsl connections
* new genconn interfaces to make a standardized environment to run SSH/WSL commands via `sh -c`. also create better quoting functions that are composable
* replace html/template with text/template for shell command templating (avoids special chars getting turned into HTML entities, breaking the commands)
* do not reinstall wsh if the installed version has a higher version (prevents flip-flopping on shared systems)
* simplify clientOs/clientArch detection. use `uname -sm`. also validate the os/arch combo as compatible with our builds.
* replace CpHostToRemote with CpWshToRemote. hard codes wsh paths inside of the function instead of having them passed in (quoting restrictions)
* new SyncBuffer class to use with commands that properly synchronizes Writes/String output
* fix setTermSize to actually update DB with terminal size
