parser: fix formatting enum and interface decl with comments (related #20202)

[yuyi98]

This PR fix formatting enum and interface decl with comments (related #20202).

• Fix formatting enum and interface decl with comments.
• Add tests.

enum ABC  // enum ABC
{
	// aaa
	aaa
}

interface Abc   // interface Abc
{
	a int
	get_info() string
}

fmt to:

enum ABC { // enum ABC
	// aaa
	aaa
}

interface Abc { // interface Abc
	a int
	get_info() string
}