amp-ima-video: `hideControls()` does not fully hide controls

[alanorozco]

#20760 introduces support for <amp-ima-video dock>. In docked mode, custom mini controls are displayed. Even though docking requested ima-video to hideControls, the latter will still display them when the video is paused, effectively showing two sets of controls at a time.

This can be approached in one of two ways:

1. Honor the result of dynamic hideControls to hide them regardless of playing state. I don't believe this would break any use-cases, since hideControls calls are dynamic and should in theory be superseded by showControls when the calling module requires it. This may require slight amp-ima-video refactoring (maybe) and additional internal postMessage APIs (doubtful).

2. Support force in hideControls. This has the unfortunate side-effect of having to backfill all players to support this parameter. This would still require additional changes to amp-ima-video, including necessary postMessage API changes to pass the flag through. However, flags like force should generally be avoided, so I'm not in favor of this API unless, for some reason, amp-ima-video UX requires decoupling of hiding use-cases (unlikely).

/to @torch2424
/cc @aghassemi

[torch2424]

Also adding @curseagain , in case you are interested in picking this up (Would improve video docking support if your team is interested in that). 😄

[curseagain]

Hello all! Somehow I missed this, but I'll pick this ticket up next. Thanks!