[clangd] Show size, offset and padding for bit fields on hover

Examle:
```
struct test {
	char a;
	char b : 3;
	char c : 5;
	int d;
	int e : 27;
};
```

{F27617774}
{F27617776}
{F27617777}
{F27617780}

Reviewed By: sammccall

Differential Revision: https://reviews.llvm.org/D151128