Refactor: Decouple *Client types from Any* types (#60)

* Decouple `*Client` types from `Any*` types

* Remove unused bounds and imports

* Fix tests

* Remove commented code

* Fix warnings

* Fix more warnings

* ClientTypes should only exist on ClientKeeper

* Finish "ClientTypes should only exist on ClientKeeper"

* Get rid of `GlobalDefs`

* fix tests

* remove unused functions

* Proc-macros for `Any*` types + Protobuf generation

* Move client types to a separate crate

* fix tests

* remove ics18-relayer

* make `downcast` and `wrap` return Option

* HostFunctions is now the responsibility of Clients

* Make `ClientType` - `str`

* Finish 'HostFunctions is now the responsibility of Clients'

* cargo fix & fmt

* Clean up dependencies

* re-introduce host consensus state proofs

* fix compilation

* remove clients

* cargo fmt

Co-authored-by: Seun Lanlege <[email protected]>