txtar: add UTF-8 and comment parsing test

[saurabhgame]

txtar: add UTF-8 test case in TestParse

Adds a new test case for the txtar package to verify that:

Parse correctly handles UTF-8 characters in file contents.
Leading comment lines are preserved properly.
This improves test coverage for non-ASCII content and ensures
comment parsing works as expected.

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Patch Set 1:

(1 comment)

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(1 comment)

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This PR (HEAD: 920f684) has been imported to Gerrit for code review.

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