Made ThreadX object names const-qualifiable behind an option

[fdesbiens]

Fixes #61

Object names are exposed as writable pointers throughout the kernel API, which rejects string literals in C++ and lets callers modify retained names. Information services return those names through writable double pointers.

Create services, control blocks, information services, modules and trace registration now preserve const qualification, behind TX_ENABLE_CONST_NAMES. The option defaults to off, so a build that says nothing gets exactly the types it got before. It is opt-in rather than opt-out because it changes the type of a public struct field: application code that copies a name into a writable CHAR * stops compiling, which is a reasonable thing to ask of a minor release and not of a patch one. The FreeRTOS adapter holds the name it retrieves in a TX_NAME_CONST pointer so it matches whichever declaration tx_thread_info_get has, and keeps its writable return type through an explicit MISRA C:2012 Rule 11.8 deviation, because that signature is part of the FreeRTOS API.

Two things the const build reaches that the default does not. _txm_module_manager_object_name_compare and the _txe_*_create stubs in the block pool parameters test took the name as CHAR *, and both arrived after this branch was written. TX_CHAR_TO_UCHAR_POINTER_CONVERT is used in exactly two places, both of them reading an object name in _tx_trace_object_register, and every form of that macro but the MISRA one casts the qualifier away without saying so; the conversion is now const in and const out, so nothing launders const to make the build pass.

Default build: all seven host configurations and all five SMP configurations build with zero warnings and pass -- 113/113 on five host configurations, 100/100 on the two MISRA builds, 118/118 on SMP, and 3/3 FreeRTOS. With TX_ENABLE_CONST_NAMES set, the host default and both MISRA configurations, the SMP trace configuration and the FreeRTOS adapter build with zero warnings and pass. Only the trace configurations compile _tx_trace_object_register and only the MISRA ones report a discarded qualifier, so the default configuration alone proves neither.

Matching changes are prepared in USBX and GUIX, and the user guide has already merged. Each of them describes the qualification as the default and needs the same switch. NetX Duo's NX_PACKET_DEBUG macro assigns a thread name into a writable CHAR * field, which the option surfaces; it is behind NX_ENABLE_PACKET_DEBUG_INFO and no default configuration builds it. FileX and LevelX need no changes.