Let a user claim he owns an asset

[straumat]

• Add in tapd mock server a verify-asset-ownership method returning, true, false or error.
• Add an integration test on asset ownership verification.
• Add a new type of request: ADD_OWNERSHIP_PROOF_REQUEST with the following parameters: assetId, scriptKey, outpoint and proof.
• On user asset list page, add a button to claim you are the creator. It will ask assetId, if issuance proof is found, it will display a form with assetid, scriptKey, outpoint and explanation. User will be able to entier its proof.
• Add a bach calling verify-asset-ownership - Find issuance proof and verify user proof -> if ok, change the creator of the asset.