Adapt UI to the new API (step 1)

[joseivanlopez]

First steps adapting the UI to use the new HTTP API. The goal is to define where to place everything, to adapt the code according the new API types, and to adapt the hooks according to the new API. There are many things still using the old API (e.g., users, software, hostname, etc). They will be adapted later once the new API is ready for them.

Meaningful changes:

• api.ts: contains all the calls to the http API.
• /api: contains the types provides by the API.
• /hooks/api.ts: contains all the hooks/queries to directly interact with the API.
• /hooks/[scope]: contains hooks for a concrete scope (e.g., storage). These hooks do not introduce new queries but use select over an API query.
• /helpers: contains helpers for the types of the API.

Special remarks:

• The UI code should directly use the types provided by the API. Defining own types should be done as last resort.
• Tests are not fixed yet. It will be done little by little while fixing each page.
• All pages must be revisited, checked and fixed.

[coveralls]

coverage: 64.404% (+0.3%) from 64.11%
when pulling de2d0fe on storage-ui-new-api
into ef9f458 on api-v2.

[coveralls]

coverage: 76.091% (+12.0%) from 64.118%
when pulling 243ab8c on storage-ui-new-api
into a6c2788 on api-v2.

[dgdavid]

Thanks a lot for such a huge work @joseivanlopez!

Let's go ahead with the merge in order to been able to start fixing pending stuff ASAP.