Remove auto-discovery of appdir

[xsawyerx]

The auto-discovery feature of Dancer2 is no longer necessary and impedes the ability to have the application directory separate from where the code library actually is.

It's magic when magic isn't necessary.

[sakshee3]

@xsawyerx which auto-discovery feature is left? since you already removed the appdir (if there is) which is in the current dir.

[veryrusty]

@sakshee3 See Dancer2::Core::Role::HasLocation->_build_location

[xsawyerx]

Note to self: If there is an appdir, why do we still run this code? I don't mind keeping it if there is no appdir configured.