This was done to purge superfluous files from Doom's project structure
and simplify its entry points. And with early-init.el now acting as
Doom's universal bootstrapper (see c05e615), we don't have enough
bootstrap logic to warrant being its own file.
Also removes the redundant version check, given doom.el is assured to be
loaded before doom-cli, and performs its own check.
Ref: c05e61536e
948f9461a7