The conversion from a known path prefix to a variable is now done in a
case-insensitive way. This means that if the variable `{storage}` has
value `S:\Flamenco`, a path `s:\flamenco\project\file.blend` will be
recognised and replaced with `{storage}\project\file.blend`.
This happens uniformly, regardless of the platform. So also on Linux,
which has a case-sensitive filesystem, this matching is done in a
case-insensitive way. It is very unlikely that a Flamenco configuration
has two separate variables, for paths that only differ in their case.
Fixes: #104336 Drive letter case mismatch causes two way variables not
to work correctly
3fb73c6c9a