* chore: move app proxying code to workspaceapps pkg
Moves path-app, subdomain-app and reconnecting PTY proxying to the new
workspaceapps.WorkspaceAppServer struct. This is in preparation for
external workspace proxies.
Updates app logout flow to avoid redirecting to coder-logout.${app_host}
on logout. Instead, all subdomain app tokens owned by the logging-out
user will be deleted every time you logout for simplicity sake.
Tests will remain in their original package, pending being moved to an
apptest package (or similar).
Co-authored-by: Steven Masley <stevenmasley@coder.com>
