feat: remove empty lines

[kazushisan]

this change will make ts-remove-unused handle empty lines in a more sophisticated manner.

• removes leading empty lines from files that were edited
• removes trailing empty lines from files that were edited (limits the line break to max of 1)
• if the edit results in 3 or more consecutive line breaks, it will limit the line break to 2

example: when const remove is not used in the following file

export const a = 'a';

export const remove = 'remove';

export const a2 = 'a2';

before

export const a = 'a';


export const a2 = 'a2';

after

export const a = 'a';

export const a2 = 'a2';