Update tst_QSvgRenderer(1)

Extract the data from fillRule and opacity functions and add them
to *_data() functions. This separates data from the actual test.
Also, use literals to construct strings and use constexpr std::array
to prepare the data at compile time.

Finally, move the test related to group opacity to its own test
function.

Pick-to: 6.12 6.11
Change-Id: I6f6a46334f6b6095fcb164b7d5e98e9ac7d8ed33
Reviewed-by: Robert Löhning <robert.loehning@qt.io>