opt: only write StructEnd while WriteEmpty()

[AsterDY]

What type of PR is this?

optimize

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• This PR title match the format: <type>(optional scope): <description>
• The description of this PR title is user-oriented and clear enough for others to understand.
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• opt: only write StructEnd while WriteEmpty()
• opt: support incorrect quoted go.tag annotation input
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(Optional) Which issue(s) this PR fixes:

when defaulted/required field is a self-referenced struct type, WriteEmpty() may introduce dead loop since it recursively write empty value for every fields of the struct

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