[Foundation] Add constant gas fees

[Olshansk]

Objective

Add transaction/gas fees to poktroll.

Origin Document

https://docs.cosmos.network/main/learn/beginner/gas-fees

https://www.notion.so/buildwithgrove/Proof-submission-cost-Tx-fee-vs-Spend-coins-044bcab72c1d4aef8dba523bd9bdf42d?pvs=4

Goals

• Parity with Morse w.r.t Tx Fees
• Unblock poktscan from deserializing tx fees
• Learning & understanding how cosmos gas fees work

Deliverables

• Set a constant tx fee for all transactions
• Ensure this is part of LocalNet and future TestNets

Non-goals / Non-deliverables

• Using variable gas meter logic

General deliverables

• Comments: Add/update TODOs and comments alongside the source code so it is easier to follow.
• Testing: Add new tests (unit and/or E2E) to the test suite.
• Makefile: Add new targets to the Makefile to make the new functionality easier to use.
• Documentation: Update architectural or development READMEs; use mermaid diagrams where appropriate.

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Creator: @Olshansk
Co-Owners: @okdas

[okdas]

@Olshansk I've added the gas fees in #768. They're not constant, though. I can look into that to see if constant fees can be easily configured.

[okdas]

I flipped the config temporarily in TestNet, and

• faucet broke as it required a fee configuration. Error:

  err: Error: Broadcasting transaction failed with code 13 (codespace: sdk). Log: insufficient fees; got:  required: 1upokt: insufficient fee
  

• All CLI commands that we have in documentation also stopped working due to a similar issue. So we either need to change the documentation or CLI defaults.

Will take a look at both when I start working on the ticket.

[Olshansk]

@okdas Once you take a look at it, let's go with CLI defaults (if it's possible) and just document the flag in the user guide in one spot.

[okdas]

Related doc: https://www.notion.so/buildwithgrove/Proof-submission-cost-Tx-fee-vs-Spend-coins-044bcab72c1d4aef8dba523bd9bdf42d?pvs=4