fmt: fix formating non-unsafe blocks with break line (fix #22900)

[yuyi98]

This PR fix formating non-unsafe blocks with break line (fix #22900).

• Fix formating non-unsafe blocks with break line.
• Add test.

blocks_keep.vv

fn main() {
	{
		println('(1/3) My first small scope')
		//
	}

	{
		println('(2/3) My second small scope')
		//
	}
	// A line below prevents the line removal

	{
		println('(3/3) My Third small scope')
	}
}

_{Huly®: V_0.6-21346}

[spytheman]

Excellent work.