fixes#12539, refs #21636
`evalInclude` now uses `getPIdent` to check if a symbol isn't `/`
anymore instead of assuming it's an ident, which it's not when used in
templates. Also it just checks if the symbol is `as` now, because there
are other infix operators that could be used like `/../`.
It also works with prefix operators now by copying what was done in
#21636.