Introduces a command to manually set urgency, as well as rendering of
urgent views, sending the IPC event, removing urgency after focused for
one second, and matching urgent views via criteria.
When you spawn a process with the exec command, sway now notes the
workspace you had focused and the pid of the child process, then assigns
that workspace to the child when its window appears.
Some of this is carried over from sway 0.15, but with some major
refactoring and centralization of state.