Media Player volume up/down requires SUPPORT_VOLUME_SET but not SUPPORT_VOLUME_STEP

[andrewsayre]

Home Assistant release with the issue: 0.92.0

Last working Home Assistant release (if known): < 0.92.0

Operating environment (Hass.io/Docker/Windows/etc.): All

Component/platform: media_player

Description of problem:
#22878 introduced a gate that checks a media player platform reports a support feature flag corresponding to a service call before invoking the service. volume_down and volume_up were mapped to SUPPORT_VOLUME_SET but should allow SUPPORT_VOLUME_STEP. This affects platforms that only support stepping the volume up/down and not setting it to an explicit value.

Additional notes:*
The gate should check for either SUPPORT_VOLUME_SET or SUPPORT_VOLUME_STEP in required features.

[andrewsayre]

Reported by user qq discord