wrap: correctly override dependency names with capital letters
wrap: correctly override dependency names with capital letters

When we do wrap resolution, we do a case-insensitive lookup because
keys, i.e. `dep_name = variable_name`, are case insensitive. In order to
check whether we should process a subproject, we need to know if the
lowercased dependency name matches.

We do this by looking up the lowercase name, and assuming that the
stored name is also lowercase. But for dependency_names, this isn't "case
insensitive and stored in lowercase" so we need to manually force it to
be consistent.

Likewise, when looking up the wrap name (which works like
dependency_names and doesn't need a provide section at all) the disk
filename of the wrap file is case sensitive, but needs to be manually
forced for consistency.

mesonbuild/meson,pexip/meson,pexip/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,mesonbuild/meson,pexip/meson,pexip/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson,mesonbuild/meson,pexip/meson,pexip/meson,pexip/meson,pexip/meson,mesonbuild/meson,pexip/meson,mesonbuild/meson