This fixes darktable-org#695.

Fix the path to the user directory on Windows preventing crash on startup

scripts so that we don't try and update them, since the directory they
are installed in is not a git directory and most likely not writable.

…te_fix

tools/script_manager - added check in update scripts for the bundled

installed scripts are updated in the correct directory.

tools/script_manager.lua - added dir to update scripts so that user installed scripts are updated in their installed directory

Document where to actually find the scripts menu
because it took me much longer than it should have.

I have the lua-scripts repo cloned in $HOME/.config/darktable/lua

Since darktable a4003bc
(darktable-org/darktable@a4003bc)
(PR darktable-org/darktable#20848) removed the direct invocation of
the user luarc from lua/init.c, that responsibility moved to
script_manager.  But it was only called in the `if system_based` case,
so my luarc was never loaded.

This commit pulls the user luarc script loading up so that it runs in
both modes.

Document where to find script manager in UI

Load user luarc files for users that have their own lua-scripts