Persistent device profiles and improvements

This MR changes/improves a bit the current Lua configuration in several ways:

• The device activation module has been ported to Lua in a new policy-device-profile.lua script. This is because all the wireplumber policies are written in Lua, and we want to keep consistency between all of them, especially with policy-bluetooth.lua which also changes profiles.

• A new option in 40-device-defaults.lua is added to define persistent profiles per device. A persistent profile is a profile that will never change, even if a new one with higher priority became available. This is especially useful for off and pro-audio profiles, we don't want them to change on EnumProfiles event if the user explicitly selected them. See #138 for more info.

• Renames default-routes.lua to policy-device-routes.lua to make the configuration more consistent. The storing of the default routes logic will eventually need to be implemented in a C module-default-routes, similar to module-default-profile.