beesh: Allow caller to add wget options

When wget is used (by the default bee_download), add options from the
variable BEE_WGET_OPTS to the command line.

This allows the user to add an authorization header, when the file is
pulled from a private repository, for example

    SRCURL[0]="https://github.molgen.mpg.de/api/v3/repos/mariux64/linux/tarball/mariux-$KERNELVERSION-$PKGREVISION mariux-$KERNELVERSION-$PKGREVISION.tar.gz"
    BEE_WGET_OPTS=(--header="Authorization: Bearer $(cat ~/.bee_gh_token)")

src/beesh.sh.in

@@ -282,6 +282,7 @@ function fetch_one_file() {
                 --output-document="${F}/${file}.tmp" \
                 --timeout=60 \
                 --tries=1 \
+                "${BEE_WGET_OPTS[@]}" \
                 "${url}"
             if [ ! -s "${F}/${file}.tmp" ] ; then
                 print_error "ERROR: ${F}/${file}.tmp is empty, download failed."