Improve stub server

[hasufell]

1. expose a cli option to start the stub server in test-mode
2. add an endpoint to insert pool metadata manually in test-mode

Related: #97

[hasufell]

I really don't know what's going on with the hashes... I'm inserting the exact same metadata from testnet into the SMASH mock DB manually and the hash will not match the one from testnet... the wallet will always barf out:

[cardano-wallet.pools-engine:Info:84] [2020-10-23 16:55:22.44 UTC] Fetching metadata with hash cc019105 from http://localhost:3100/api/v1/metadata/5ee7591bf30eaa4f5dce70b4a676eb02d5be8012d188f04fe3beffb0/cc019105f084aef2a956b2f7f2c0bf4e747bf7696705312c244620089429df6f
[cardano-wallet.pools-engine:Warning:84] [2020-10-23 16:55:22.45 UTC] Failed to fetch metadata with hash cc019105: Metadata hash mismatch. Saw: e8685e47a97c73fd04735b10c51e0b1fe3a6029490c90bf8e85fc7b88cef2021, but expected: cc019105f084aef2a956b2f7f2c0bf4e747bf7696705312c244620089429df6f

---

Edit: figured it out

[ksaric]

Please fix the inlined code and will approve and merge.

[ksaric]

Also, I think you will need to rebase. I would have fixed the branch but I see you forked it. In the future, please keep the branches in this repo. If you don't have permission, just ping me in Slack.

[hasufell]

Also, I think you will need to rebase. I would have fixed the branch but I see you forked it. In the future, please keep the branches in this repo. If you don't have permission, just ping me in Slack.

Yes, I don't think I have permissions

[ksaric]

Also, I think you will need to rebase. I would have fixed the branch but I see you forked it. In the future, please keep the branches in this repo. If you don't have permission, just ping me in Slack.

Yes, I don't think I have permissions

Added you, you now have write access.

[hasufell]

Applied comments and rebased

[ksaric]

Better.

[ksaric]

bors r+

[hasufell]

Btw, unrelated to this PR, but I noticed during compilation

[21 of 23] Compiling Cardano.SMASH.DBSync.SmashDbSync

/home/jule/git/iohk/smash-clean/src/Cardano/SMASH/DBSync/SmashDbSync.hs:221:9: warning: [-Wincomplete-patterns]
    Pattern match(es) are non-exhaustive
    In a case alternative:
        Patterns not matched:
            (GenesisByron _)
            (GenesisShelley _)
    |
221 |         case genCfg of
    |         ^^^^^^^^^^^^^^...

[iohk-bors]

Build succeeded:

• ci/hydra-eval
• buildkite/smash
• ci/hydra-build:required