* refactor: fix clang-tidy vector operation warnings
Fix vector population performance-inefficient-vector-operation warnings
generated by clang-tidy
* refactor: fix clang-tidy emplace_back warnings
In cases where a temporary is created to be passed
to push_back(), replace it with emplace_back().
Warning: modernize-use-emplace
* refactor: fix clang-tidy loop iteration warnings
When practical, use range-based for loops instead of C-style for loops.
clang-tiny check: modernize-loop-convert
* refactor: fix clang-tidy string initialize warning
Remove redundant empty string initialization.
clang-tidy check: readability-redundant-string-init
* add notice to files being removed
* add gin version of function_template.h
* rename callback.h to avoid confliction
* add gin version of callback_converter
* add gin converter for OnceCallback
* remove callback_converter_gin_adapter.h
* remove gin_util.h and gin_utils.h
* fix lint warning
* add helper for setting methods
