Add script & options to install missing tools & dependencies

From "README.rst":

diffoscope requires Python 3 and the following modules available on PyPI: libarchive-c, python-magic. The various comparators rely on external commands being available. To get a list of them, please run:

$ bin/diffoscope --list-tools

which only show how to receive list of stuff to install (python3, 2 modules [libarchive-c,python-magic] from PyPI, and list of packages from diffoscope command) but not how to install thus affecting both user who cloned the repo (need to figure out how to install by himself without info in documentation) and Docker container, see comments below : #104 (comment 164485)

The issue is about adding:

1. script like installMissingDeps.sh which will install python3 & required python modules.
2. options to diffoscope that will install missing tools (from the --list-tools) by passing them to supported package manager (apt in debian, pacman in arch, etc...) such as --install-missing-tools (or adding a script installMissingTools.sh that will do that based on output of diffoscope)
3. the option --install-missing-tools can receive arguments of what to install like:

all-duplicates for all tools including duplicates? (tools who provide the same command? or same effect [both can extract file type X])

all like the above but install only the first tool for needed command/operation.

all-but which can receive arguments for types of diffs usage, such as "android" (as android related tools take lot of space, due to need for java & android- packages)

android which will list the related packages for apk-diffing like (apktool, enjarify, androguard, dexdump, etc...)

and other bundles like android (maybe IOS? which install all the stuff for .IPA file comparing)