* echo: handle multibyte escape sequences
Bug was reported, with root cause analysis, by kkew3
Added tests were derived from test cases provided by kkew3
See https://github.com/uutils/coreutils/issues/6741
* Use concrete type
* Fix MSRV issue
* Fix non-UTF-8 argument handling
* Fix MSRV issue
* Fix Clippy violation
* Fix compiler warning
* Address PR comments
* Add MSRV TODO comments
* echo: use stdout_only_bytes instead of stdout_is_bytes
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Co-authored-by: Daniel Hofstetter <daniel.hofstetter@42dh.com>
* fix: use settings to allow leading hyphen and trailing var arg
fixes: https://github.com/uutils/coreutils/issues/1873
* test: add test cases
* test: add more test cases with different order in hyphen values
* chore: add comment to explain why we need TrailingVarArg