This also introduces `always_false` technique instead of `sizeof` trick for unsupported D-Bus type representation static assert. This one is more expressive and leads to more specific, more revealing compiler error messages.
* feat: support serialization of array, span and unordered_map
* fix some spelling mistakes
* docs: update table of valid c++ types
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Co-authored-by: Marcel Hellwig <github@cookiesoft.de>