Tobias Berner authored Jan 24, 2022 and Adriaan de Groot committed May 23, 2022

Summary:
* add search module for pciconf binary
* prefer pciconf over lspci if found (maybe add an option to override?)
* add backend.h containing 'pciconv -lv' respectively 'lscpi -v'

Test Plan:

Reviewers: #freebsd

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