Add QNX 7 support

[dcalavrezo-qorix]

• Add QNX SDP 7.1 support alongside existing 8.0.0.
• Introduce a qnx_version constraint and new platforms (x86_64-qnx7_1, aarch64-qnx7_1) to let multiple SDPs coexist.
• Include QNX 7.1 toolchain repository templates and wiring for qcc and mkifs (with license server propagation).