TrustAtoms allow content over 900 bytes, stored in "extra" entry

[harlantwood]

Feature

If content exceeds 900 bytes:

• In the link tag: it ends with … (unicode char) as a hint

• Full content is stored in the extra Entry under the key __FULL_TRUST_ATOM_CONTENT__

    eg: extra is equal to
    { "__FULL_TRUST_ATOM_CONTENT__": "abcdefg....",  ... }
  

• Validation error if user passes in extra hash with __FULL_TRUST_ATOM_CONTENT__ as top level key

    eg: if user sends us an extra hash with:
    { "__FULL_TRUST_ATOM_CONTENT__": "zzzzz....",  ... }
    and they also send content > 900 bytes: "aaaa..."
  

---

let's have a test that pushes in 1000 bytes of content, and:

ensure that we get an extra hash in the link tag
retrieve the content from the extra entry and validate that it is correct

[harlantwood]

from discussion:

trustatom::create_trust_atom( 
  target: string version of EntryHash // TBH would be better to be more readable thing
  content: string // semantic
  value: number as string // scalar
  extra: { foo: "bar", bar2: "baz", baz2: 333 } // valid
  extra: { {foo: "bar"}, bar2: "baz", baz2: 333 } // invalid
  extra: [ "foo" ] // invalid
)