Support module-manager kernels in CMake builds

[fdesbiens]

CMake can build the standard and SMP kernels, but it cannot build a ThreadX kernel with module-manager support. Projects using FetchContent must patch the ThreadX build to select module ports and module-manager sources. This tracks the request in #432.

Requirements:

• Add a CMake cache option for a module-manager kernel, disabled by default. Keep the existing threadx target and azrtos::threadx alias usable by consumers.
• Select the matching module port implementation and compile the common and port-specific module-manager sources. Publish the headers and compile settings needed by applications that use the module-manager APIs.
• Fail configuration with a clear message when the selected architecture, toolchain, or SMP combination has no supported module-manager build.
• Document the option, the initially supported ports, and how a FetchContent consumer enables it. Keep the loadable module library as a separate build product.
• Add CMake/Ninja build coverage for each supported module-manager port and a consumer check that compiles against the module-manager API. Confirm the default and SMP builds still work.