Package/sensei: PR request for SENSEI (in situ analysis tool) recipe (#12973)

* Created an initial recipe for Sensei

* Cleanup syntax

* Small fixes for the Sensei recipe

* Cosmetic fixes to comply with PEP8

* More cosmetic fixes before PR

* Added more documentation before PR

* Fixed flake8 errors

* Fixes following PR review

* Fixes to pass Flake8 passes

* Some changes following PR review and support for SENSEI 3

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

Co-Authored-By: Axel Huebl <axel.huebl@plasma.ninja>

* Fixed Flake8 errors