Extend tst_qxmlstream::readBack() to all Unicode characters

... not just those in the BMP.

The use of char32_t makes the isValid helper function easier to
read. Its passing to write() is enabled by the recent port to
QAnyStringView, which has a char32_t ctor.

Split into per-plane executions of the test function to avoid
running into timeouts on asan builds down the road.

As a drive-by, replace use of QPair with a proper struct, and
make the intervals symmetrically inclusive the bounds.

Pick-to: 6.5
Change-Id: I2c6858d7e6a88f448eac1b1e124d7d7b82828d4c
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

0 files changed, 0 insertions, 0 deletions