Blender Git Loki

Fix T88466: Sound strips prevent strip rendering

When sound strip is above another strip such as movie strip, it prevents
from rendering movie strip.

This bug was introduced in 0b7744f4da66. Function `must_render_strip()`
checks if there is any strip with `SEQ_BLEND_REPLACE` blending and
considers this strip as lowest strip in stack. Sound strips do have this
blend mode set, which caused the bug.

Remove all sound strips and muted strips from stack collection before
checking with `must_render_strip()` function