Add scripts to generate Debian packages of Fluoride dependencies

To build Fluoride on Linux, there are dependencies that are not usually
provided by Linux package managers. This patch adds libchrome and
modp_b64 package generators to make building them easier on Debian-based
distros.

Bug: 179821440
Tag: #floss
Test: None
Change-Id: I93c6583d58635c65dbfbeea2ff556f09585225d5