Bianjie/lcd implementation

[HaoyangLiu]

Proceed from: #2147
I just changed the source repo. The code is the same. I'm so sorry for bring troubles for all of you.

[cwgoes]

Thanks for the PR. Can we please split this, as possible, into separate PRs addressing individual concerns? That will help us review faster and ensure code quality.

See some background discussion at #2173 (comment).

[fedekunze]

@cwgoes this is the initial scope of the PR #2118 (comment):

1. Add query store proof verification
2. Add swagger-ui
3. Lcd can connect to multiply full nodes and will do load balancing
4. Support modular APIs. Currently we only support key management, token query, token send, stake query, node version query.

[cwgoes]

Can we break (1), (2), (3), and (4) into separate PRs? That seems like a natural separation.

Referencing also this section in CONTRIBUTING.md:

To accommodate review process we suggest that PRs are categorically broken up. Ideally each PR addresses only a single issue. Additionally, as much as possible code refactoring and cleanup should be submitted as a separate PRs from bugfixes/feature-additions.

(I realize this is a pain but I think we need to start being strict about it at this stage in the development cycle especially)

[HaoyangLiu]

@cwgoes
Your suggestion is very thoughtful. The current PR is too big to review. It affects more than 5 thousand lines code. Indeed, this is a big trouble for code reviewer. Thanks very much for all reviewers: @fedekunze @alexanderbez .
Next I will split this PR into several parts:

• PR1: Proof build and verification related
• PR2:
  Add lite-server with swagger-ui and
  Add client manager(load balancing, very small change)
  Add APIs of these modules: transaction(1 API), bank(1 API) and auth(1 API).
• PR3: Add APIs of the rest modules: key managerment(7 APIs), staking(11 APIs)
• PR4: Add APIs of the rest modules: slasking(2 APIs) and governance(8 APIs).
• PR5: Update gaia-lite spec to keep it consistent with its implemenation.
  @cwgoes Do you think this is reasonable?

[fedekunze]

@HaoyangLiu remember to add the prefix R4R to the title and the label ready-for-review when your PRs are done so we can review and merge it faster

[HaoyangLiu]

@fedekunze Thanks for your advice. I have added R4R in the title of #2192 and #2199