remove download scripts, consolidate into script

most of them were just calling the gitclone script,
so remove them.

the grub script was treating gnulib as a dependency.
i've now added the ability to grab 1 dependency, in
the gitclone script (it should be expanded later to
support multiple dependencies)

the gitclone script has been renamed to "fetch".
the "fetch_trees" script does more or less the same
thing, but calls "fetch" and handles multiple revisions
if a project needs that

this is more efficient, and slightly reduces the code
size of lbmk!

Signed-off-by: Leah Rowe <leah@libreboot.org>

resources/scripts/build/module/memtest86plus

@@ -31,7 +31,7 @@ set -u -e
 printf "Building MemTest86+\n"
 
 if [ ! -d "memtest86plus/" ]; then
-	./download memtest86plus
+	./fetch memtest86plus
 fi
 
 make -j$(nproc) -BC memtest86plus