Allow for visitor ordering or multi-pass configurations

It seems all the issues I've encountered with lightningcss involve the inability to visit a token more than once or to control visitor ordering. If you set a no-op FunctionExit visitor, a function will be visited after its arguments, but then it won't get minified because it has already been visited. Perhaps it should be possible to set a FunctionExit visitor that does nothing but imply a function should be evaluated after its arguments without overriding the function's behavior... or this could be the default (wherein functions are always evaluated after arguments). Or a visitor to a token could be configured to occur before other tokens.

Start by tracing how lightningcss handles visitor traversal, particularly FunctionExit visitors and function arguments. Compare the current single-visit behavior with the requested multi-pass or configurable ordering alternatives, then define tests that demonstrate the intended ordering and confirm that functions are still minified.