The only output_enable caller is now apply_output_config. Stop calling
apply_output_config from output_enable to simplify the code and avoid
the back-and-forth between these two functions.
output_enable is now the symmetric of output_disable: it just marks the
output as enabled and performs bookkeeping (e.g. creating teh default
workspace). It is called from apply_output_config after the output
commit, so that it can read the current output state and act
accordingly.
This change also allows us to avoid an extraneous wlr_output_commit.
References: https://github.com/swaywm/sway/issues/4921
f5fa0c7124