Use UTF-8 in test results

Use UTF-8 charset in test results (All built in test cases and default test result templates)
like adding this in to the HTML report:

but need to use UTF-8 in case of
csv output
text output
any other built in output

Start by locating the built-in test result templates and output entry points for HTML, CSV, text, and other formats. Compare their charset handling, then run the existing test-result cases to verify that every built-in output consistently uses UTF-8.

Written by the indexing model from the issue text.