Candid type selector (#544)

* replace dhall with toml

* checkpoint

* checkpoint

* checkpoint

* checkpoint

* checkpoint

* checkpoint

* checkpoint

* random works

* test

* fix

* fix

* Refactor Rust bindgen with the new config (#546)

* checkpoint

* checkpoint

* connect with didc and test

* checkpoint

* vis

* vis

* checkpoint

* fix merging semantics

* checkpoint

* fix

* fix

* fix root config fallback

* checkpoint

* add unmatched config

* fix attr

* handlebar

* update test, diff is only space and newline

* forget to commit test

* move pp_actor inside impl

* fix

* refactor

* init args

* add test

* add_config

* clippy

* changelog and bump version