Add function call inout passing style

In current implementation of cppfront the following code
```cpp
f2: (inout x) -> _ = {
    return x * 2;
}

main: () -> int = {
    x := 21;
    std::cout << f2(x) << std::endl;
}
```
Generates:
```cpp
[[nodiscard]] auto f2(auto& x) -> auto{
    return x * 2;
}

[[nodiscard]] auto main() -> int{
    auto x {21};
    std::cout << f2(std::move(x)) << std::endl;
}
```
and fail to compile as move from last use make the call to `f2`
incompatible with requirements of the `f2` function
(function requires lvalue reference and receives rvalue reference).

This change introduce possibility to add `inout` passing style
to function call to emphasize that it has to be passed without the move.
After this change the original code can be fixed to:
```cpp
f2: (inout x) -> _ = {
    return x * 2;
}

main: () -> int = {
    x := 21;
    std::cout << f2(inout x) << std::endl;
}
```
which will generate:
```cpp
[[nodiscard]] auto f2(auto& x) -> auto{
    return x * 2;
}

[[nodiscard]] auto main() -> int{
    auto x {21};
    std::cout << f2(      x) << std::endl;
}
```

Author: filipsajdak

source/cppfront.cpp

@@ -3230,6 +3230,7 @@ class cppfront
                     x.pass == passing_style::out
                     || x.pass == passing_style::move
                     || x.pass == passing_style::forward
+                    || x.pass == passing_style::inout
                 );
                 if (x.pass == passing_style::out) {
                     is_out = true;
@@ -3240,6 +3241,10 @@ class cppfront
                     printer.print_cpp2("std::move(", n.position());
                     offset = 6;    // because we're replacing "move " (followed by at least one space) with "std::move("
                 }
+                else if (x.pass == passing_style::inout) {
+                    is_out = true;
+                    offset = -6;   // because we're replacing "inout " (followed by at least one space) with nothing
+                }
             }
 
             if (is_out) {

source/parse.h

@@ -3126,6 +3126,7 @@ class parser
                 dir == passing_style::out
                 || dir == passing_style::move
                 || dir == passing_style::forward
+                || dir == passing_style::inout
                 )
             && peek(1)
             && peek(1)->type() == lexeme::Identifier