Add a command line option that prints the toolchain hierarchy for a given toolchain

[ocaisa]

Reading easybuilders/easybuild-docs#288, I can see how it would be convenient if people could quickly check what the toolchain hierarchy is for a given toolchain. Something along the lines of

eb --print-toolchain-hierarchy foss,2023a

[ocaisa]

Should be as simple as

easybuild-framework/test/framework/robot.py

Lines 827 to 835 in b37f707

	fosscuda_hierarchy = get_toolchain_hierarchy({'name': 'fosscuda', 'version': '2018a'})
	self.assertEqual(fosscuda_hierarchy, [
	{'name': 'GCC', 'version': '6.4.0-2.28'},
	{'name': 'golf', 'version': '2018a'},
	{'name': 'gcccuda', 'version': '2018a'},
	{'name': 'golfc', 'version': '2018a'},
	{'name': 'gompic', 'version': '2018a'},
	{'name': 'fosscuda', 'version': '2018a'},
	])

along with some sanity checking for thetoolchain parameters (which probably also exists somewhere)