Change merge order of CLI special args to allow correct templating of taskfile global vars.

[trulede]

fixes #2090

This places CLI special args before taskfile global vars.

The tricky thing here is that e.Taskfile.Vars is used earlier to setup the e.Compiler object (TaskfileVars). Therefore, both pointers need to be assigned to the new Vars object, otherwise the compiler will operate from the previous list.

[trulede]

As a side note, I would solve the problem by adding a c.SpecialVars and the placing the processing between TaskfileEnv and TaskfileVars at the following location:

task/compiler.go

Line 111 in 14bbb32

for k, v := range c.TaskfileVars.All() {

    for k, v := range c.SpecialVars.All() {
		if err := rangeFunc(k, v); err != nil {
			return nil, err
		}
	}

but I think there are bigger plans in a different direction (#2036)?