Apparently `lxml.html.document_fromstring` (and possibly other
`lxml.html` loaders) parses byte-strings as latin1 regardless of their
actual encoding, maybe because python2, maybe because there's a super
legacy html4 parser underlying it.

Either way that means ever since loading
`static/description/index.html` files was added 10 years
ago (4bf6a7ea) `_get_desc` has been
loading these files in latin1 rather than the utf8 most people would
expect.

Add an explicit decoding phase to try and load html description files
in UTF8. Fall back to latin1 in case there are description files which
are genuinely in latin1, or even just some random-ass broken stuff
which very much isn't utf8 (the extended-ascii encodings -- of which
latin1 is one -- will happily accept and mangle any input as every
byte value is valid, utf8 is a lot more structured).

Closes #127846

closes odoo/odoo#133740

X-original-commit: 4dbc3b00
Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>