Roadmap to support AVR/8-bit chipset

[antonysigma]

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(Summarizing the discussions at https://github.com/intel/compile-time-init-build/discussions/105 ... Please feel free to revise the roadmap below.)

1. [ ] Wait for ISO C++26 standard to publish, which requires the standard library <stdexcept> to be part of the freestanding C++ toolchain;
2. [ ] Work with team behind the project avr-libstdcpp to include a subset of <stdexcept> features. https://github.com/modm-io/avr-libstdcpp?tab=readme-ov-file#notable-adaptions-and-limitations
3. [ ] If step 2 is blocked, convince the fmtlib team to remove the line #include <stdexcept> in the header-only library, or make it an optional #include similar to how #include <fmt/compile.h> is made optional.
4. [ ] If step 2 and 3 are blocked, convince the compile-time-init team to make #include <fmt/format.h> optional.
5. [ ] If step 2, 3, and 4 are all "no go", the feature is clearly stuck in a multi-team, multi-project stalemate. maybe we should give up on Microchip/Atmel AVR chipset support in the compile-time-init framework. (After all, the limited 16-bit address space, and the Harvard architecture may not justify cib's complexity.)
6. [X] Or, use an outdated version without the latest features, e.g. RLE encoding of the command router, i.e. right before #338 .