packages:
rename `errt` to `err_template`
rename `multe` to `flat_err`
rename `handler_structs` to `handler_params` with changes
logger:
move some fields to top logger
create sub logger when need
handler and sub-handler:
create sub params when need
plugin_utils:
rename `CustomSymbolCommand` to `FullCommand`
rename `SlashSymbolCommand` to `SlashCommand`