Evaluate use of Tx simulate to determine the fees

[ancazamfir]

Crate

relayer

Summary

Big Tx-es (e.g. including 30 msgs which is the default maximum) are sometimes rejected with out of gas error.

Problem Definition

We currently use the gas and fee_amount in the config file when sending a Tx. The Tx is sometimes rejected with out of gas error. Current workaround is to increase the value in the config file.
Instead we should evaluate the gas/ fee parameters at the moment we send the Tx.

Proposal

@andynog made this analysis earlier:
The REST API has a /cosmos/tx/v1beta1/simulate endpoint that you can submit a tx and it returns the gas used, you can craft a 'fake' transaction e.g. MsgSend but it does enforce a few validation (address needs to exist on chain, account sequence number) and it will return something like:

{
  "gas_info": {
    "gas_wanted": "0",
    "gas_used": "50682"
  },
  "result": {
    "data": "CgYKBHNlbmQ=",

and this just simulates and doesn't execute the transaction. Anyways, this is probably the best way found so far to find how much gas a tx will use.

Acceptance Criteria

---

For Admin Use

• Not duplicate issue
• Appropriate labels applied
• Appropriate milestone (priority) applied
• Appropriate contributors tagged
• Contributor assigned/self-assigned