Set up QNX environment in CMake kits

When a QNX Qt build is installed via the Qt installer, it's detected since VSCODEEXT-91 is fixed. However, the created CMake kit is not usable, because the QNX environment is not set.

The environment is usually set by a script in the QNX SDK.

We can locate the QNX SDK with qtpaths:

$ ~/Qt/6.7.2/qnx71_x86_64/bin/qtpaths -query QT_SYSROOT
/opt/qnx710/target/qnx7

There, we find a script to set the environment:

$ ls $(~/Qt/6.7.2/qnx71_x86_64/bin/qtpaths -query QT_SYSROOT)/../../
bsp  host  qnxsdp-env.bat  qnxsdp-env.sh  source  target

We could execute this script, grab the environment and write it into the CMake kit.