New packages: madgraph, syscalc, collier, gosam-contrib (#17601)

* Add Collier and SysCalc recipes

* Remove extra syscalc version

* Build collier with -j1 for @:1.2.4

* Add recipe for gosam-contrib

* Update gosam-contrib recipe with 'provides'

* Madgraph recipe, first version

* Finalize madgraph recipe + flake8

* Make py2 version of madgraph default; fix hash for syscalc; fix patch

* Handle virtual packages (#3)

* Update package.py

* Update packages.yaml

* Remove virtual packages - pt. 1

* Remove virtual packages - pt. 2

* Changes from review - pt. 1

* Changes from code review - pt. 2

* Update var/spack/repos/builtin/packages/collier/package.py

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

* Update var/spack/repos/builtin/packages/madgraph5amc/package.py

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

* Add hash for version 2.7.2 (available in our private mirror)

* Fixes for 2.7.3 family

* Patches for 2.7.3{.py3,}{.atlas,}

* Fix hash of syscalc

* Hack to fix concretization (2.7.3 matches 2.7.3.py3)

* Add conflict statement (reported to devs)

* Apply suggestions from code review

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

* Update package.py

* Delete madgraph5amc-2.7.2.atlas.patch

* Delete madgraph5amc-2.7.2.patch

* Update package.py

* Apply suggestions from code review

Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>

Co-authored-by: iarspider <iarpsider@gmail.com>
Co-authored-by: Adam J. Stewart <ajstewart426@gmail.com>