Allow to gets assets by account ownership

[ipr0310]

Describe the solution you'd like
As the new incoming Signum Node Version will include a new transaction type Token Ownership Transfer adjustments are necessary.
Is necessary to add support for getting the assets only owned by an account, not the issued ones.

What i mean with ownership is that the account is able to do basic token operations like: Minting, Treasury account management, etc...

It would look something like this:

Additional Context
There is the possibility to get assets by issuer (getAssetsByIssuer) but not by ownership.

Alternative option
Is possible to get the assets an account Has ownership of by just making a getAssetsByIssuer request and filter it client-side.
But by the time the chain grows, efficiency is still key.

[frankTheTank72]

@jjos2372 the current call /api?requestType=getAssetsByIssuer is not returning the correct account ( always the issuer) - can you adjust the output like on getAsset please

[jjos2372]

Should we create a new end point like getAssetsByOwner as suggested or just extend this one and make getAssetsByIssuer to return both, issued and owned?

[frankTheTank72]

i would think it is more clear to have getAssetsByOwner and getAssetsByIssuer

[frankTheTank72]

@ipr0310 fixed with beta2 and also new getAssetsByOwner