Add sbom target to Makefile and needed Lua scripts

[tuukka.pasanen_ilmi.fi]

Summary

Add sbom target to Mk/bsd.port.mk and needed Lua scripts

• Mk/LuaScripts/ports-spdx.lua: SPDX Lite 3.0.1 creating functions library
• Mk/LuaScripts/ports-spdx-traverse-deps.lua: Creates SPDX SBOM from packages and traverse thru depended packages and adding their information also

Test Plan

Apply diff and then go to some (first some package with few dependencies) and run make sbom. After a while it should output SPDX Lite 3.x JSON-LD SBOM for that specific package and include package dependencies and information.

Beware: Currently it does not use SPDX License string but licenses from FreeBSD ports. This is know issue and will be fixed in future.