c++ bindgen issues (resources/imports/includes)

## Summary
This issue buckets multiple problems to avoid opening many separate issues at once.

Each sub-item is independently reproducible and causes the generated C++ to fail to compile.

If you prefer, I can split this bucket into separate issues.

## Environment
- wit-bindgen-cli: 0.47.0
- OS: Ubuntu 22.04.5 LTS (x86_64)

clang command: `clang++ -c "$OUT/w.cpp" -I"$OUT" -o "$OUT/w.o"`

## Details

### Sub-issue 1

C++ fails to compile.

#### Reproduction
```
package demo:poc;

interface host {
resource r;
}

world w {
import host;
use host.{r};
export take: func(x: r);
}
```

### Sub-issue 2

missing `wit.h`

#### Reproduction
```
package demo:poc;

interface i {
resource r;
f: func(x: borrow);
}

world w {
export i;
}
```

### Sub-issue 3

C++ fails to compile.

#### Reproduction
```
package demo:poc;

interface i {
resource r;
take-many: func(xs: list>);
}

world w {
import i;
}
```

### Sub-issue 4

C++ fails to compile.

#### Reproduction
```
package demo:poc;

world w {
export f: func() -> result;
}
```

### Sub-issue 5

C++ fails to compile.

#### Reproduction
```
package demo:poc;

world w {
record t {
x: u32,
}

import foo: func(x: t);
}
```