Breaking down the attention API PR: part 1

[gabrieldemarmiesse]

Summary

I believe that it will be simpler to merge #8296 by breaking it down into indépendant, small PRs as much as possible. Here is the first one.

Related Issues

PR Overview

• This PR requires new unit tests [y/n] (make sure tests are included)
• This PR requires to update the documentation [y/n] (make sure the docs are up-to-date)
• This PR is backwards compatible [y/n]
• This PR changes the current API [y/n] (all API changes need to be approved by fchollet)

[farizrahman4u]

If there is some git magic we could do to assign commits to the original author for upcoming PRs that would be great.

[gabrieldemarmiesse]

Indeed, that'd be nice! Do you know how to? I can try to look it up.

[gabrieldemarmiesse]

I just found how. git commit --author="Author Name <[email protected]>". I'll do it for the next commits.

[fchollet]

Please keep in mind that I should approve all API changes before merging (which this PR includes).