Fix GH-11300: license issue: restricted unicode license headers

Closes GH-11572.

Fix conversion of ISO-2022-KR text (and add test suite)

- Truncated multi-byte characters are treated as an error
- Truncated or unrecognized escape sequences are treated as an error

Fix conversion of ISO-2022-KR text (and add test suite)

- Truncated multi-byte characters are treated as an error
- Truncated or unrecognized escape sequences are treated as an error
- ASCII control characters are not allowed to appear in the middle
of a multi-byte character

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