I temporarily removed this during the refactor so it needed to be added
back. This time I bundled it with the nbin loader code since it's all
related (will also make it easier to remove).
Fixes issues with unexpected characters breaking things when setting the
cookie (like semicolons).
This change as-is does not affect the security of code-server
itself (we've just replaced the static password with a static hash) but
if we were to add a salt in the future it would let us invalidate keys
by rehashing with a new salt which could be handy.
