fix: remove the unnecessary logic for inserting semicolons

[inottn]

Summary

fix #7611

1. We don't need to insert a semicolon for ExportDefaultDeclaration:

export default function () {} // No need to insert a semicolon
export default class MyClass {}

2. For ExportDeclaration, when a semicolon needs to be inserted, the corresponding Visit will be triggered:

export function foo() {} // No need to insert a semicolon
export const bar = 42 // It will call visit_var_decl to insert a semicolon

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

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[h-a-n-a]

Thanks. I will update tests in the upcoming PR.