Add /settings command

[grunch]

Add new command that let the user know their current settings and allow change it.

It should show values and buttons, if the user have a lightning address it must show the value and a button to disable lightning address, if the username have /showusername enabled it must show yes or no and a button to disable it, the same with /showvolume, if user have a default community it must show the name of the community and a button to disable it.