TEST: Pass arbitrary expressions as parameters

This was fixed in c60be0e78a5208075036a5c1e8b0362c9e3f62e3.
`for` statements should write results to the pipeline.

This test previously caught a bug where you couldn't pass expressions as
arguments. That is now covered by the test in commit
9f9131e118e8e66dbe40a4e945855753d4d94707.
Array expressions (`@(1,2,3)`)

Including correct handling of side-effects.

        PASH C:\> @(10)
        10
        PASH C:\> @($x = 10)
Merge pull request #107 from JayBazuzi/array-expressions

Array expressions