fix(android): Return data uris as an URI

[breautek]

Platforms affected

Android

Motivation and Context

Makes data urls returned as actual URIs instead of just the base 64 encoded data.
This sisters PR #902

Closes #420

Description

Prefixes the base64 with the data uri header.

Testing

paramedic tests passes
Manual testing

Checklist

• I've run the tests to see all new and existing tests pass
• I added automated test coverage as appropriate for this change
• Commit is prefixed with (platform) if this change only applies to one platform (e.g. (android))
• If this Pull Request resolves an issue, I linked to the issue in the text above (and used the correct keyword to close issues using keywords)
• I've updated the documentation if necessary

[jcesarmobile]

Doesn’t really fully closes #420, this only changes the behavior for android, but iOS and browser are still “broken”

[breautek]

Yah, it will be covered by #911 and #912