[Feature]: Add a query to get the total issuance of native coins

[MSNTCS]

Summary of changes

Add a new query type to support getting the issuance of native coins. This will address issue #3.

Report of required housekeeping

• [x] Github issue OR spec proposal link
• [ ] Wrote tests
• [ ] Added a relevant changelog entry to CHANGELOG.md

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(FOR ADMIN) Before merging

• [ ] Added appropriate labels to PR
• [ ] Squashed all commits, uses message "Merge pull request #XYZ: [title]" (coding standards)
• [ ] Confirm added tests are consistent with the intended behavior of changes
• [ ] Ensure all tests pass

[JoowonYun]

Just a question. Is there a reason to rewrite the cosmos base module separately?

It seems that the package was created by cosmwasm. ex)

let balance = deps.querier.query_balance(address, denom);

https://github.com/CosmWasm/cosmwasm/blob/main/packages/std/src/traits.rs

[MSNTCS]

Just a question. Is there a reason to rewrite the cosmos base module separately?

It seems that the package was created by cosmwasm. ex)

let balance = deps.querier.query_balance(address, denom);

https://github.com/CosmWasm/cosmwasm/blob/main/packages/std/src/traits.rs

That is the user's balance, what we need here is the total issuance of a native coin.