[NTRN-163] add dex stargate helpers

[NeverHappened]

task: https://hadronlabs.atlassian.net/browse/NTRN-163

this PR:

• removes build_proto stuff the repo contains for it's outdated and actually useless;
• adds a neutron_sdk::stargate::proto_types package which contains all neutron-specific proto types generated in rust;
• adds a neutron_sdk::stargate package which contains stargate query/msg helper funcs and types only for the dex module atm.

to be done in by a future release:

• add stargate helpers for the rest of the neutron modules;
• add proto generator script (partially done by @sotnikov-s, but not in scope of this PR because of time pressure);
• fix dex module imperfections (unix timestamp as i64 instead of Timestamp, Pool_metadata -> pool_metadata);
• implement PrecDec data type (used here https://github.com/neutron-org/neutron/blob/168815d3703a803f97566f2ddaf0954ac8bda203/proto/neutron/dex/params.proto#L14 and in a couple of other places).

related PRs:

• [NTRN-163] implement dex stargate contract neutron-dev-contracts#37
• [NTRN-163] add dex stargate tests neutron-integration-tests#251
• [NTRN-163] add dex stargate helpers neutronjsplus#12

[sotnikov-s]

https://github.com/neutron-org/neutron-tests/actions/runs/7111070219

[pr0n00gler]

add proto generator script (partially done by @sotnikov-s, but not in scope of this PR because of time pressure);

Could you attach at least a WIP script here?
Because we need to finish it at least

[swelf19]

LGTM.
And a suggestion, i can see there is the Name trait in prost repo - https://github.com/tokio-rs/prost/blob/master/src/name.rs#L7 which potentially could let you avoid handcrafted helpers (msg_dex, query_dex) by generating appropriate type names.

[sotnikov-s]

https://github.com/neutron-org/neutron-tests/actions/runs/7111070219

[sotnikov-s]

https://github.com/neutron-org/neutron-tests/actions/runs/7206923966

[sotnikov-s]

add proto generator script (partially done by @sotnikov-s, but not in scope of this PR because of time pressure);

Could you attach at least a WIP script here? Because we need to finish it at least

created a task for it and assigned to myself: https://hadronlabs.atlassian.net/browse/NTRN-192