Sequencer - strip theme upates

[Draise14]

Seems the theming of the strips in the sequencer has been updated, and contains more functionality in turn. Including missing datablocks.

Related task:

4231

Details

SHA-1: c64050ecd23a1f5ba81076ba9ad71b59d8f66ca9 * VSE: Timeline strip visual design updates Design updates as per #118288: - Tweak text labels (colors, drop shadows) - Strip border colors, inset outlines - Muted strips are mostly gray, and their thumbnails are faded - Overlapping strips are not semitransparent anymore - Locked stripes only in content area - Missing data blocks - Updates to meta strips w/ missing data blocks Pull Request: https://projects.blender.org/blender/blender/pulls/118581

Draw Outline Details

SHA-1: 3ac504b8f6cfab94c17a92dad9a317d0a9c1da05 * VSE: Draw outline on active unselected strips In Blender 4.1 and prior, you can tell apart the active-unselected strip because it would have no thick outline but the text would be highlighted. However, if label overlays were disabled there would be no way to know tell them apart. Solve this by drawing a subtle 1px outline on active unselected strips, using the active outline color but slightly dimmed. Pull Request: https://projects.blender.org/blender/blender/pulls/121029

Missing Data Details

SHA-1: 31e56797f0dce87df599e74dcc8f1bcff3f2436c * VSE: indicate missing media in timeline/display Sequencer timeline displays red tint & appropriate icons for strips that are missing media file (images, movies, audio, or meta strips that contain such). Sequencer preview and rendering displays missing media strips as magenta, similar to missing textures elsewhere in Blender. This is on by default, sequencer view settings have an option to turn it off. Pull Request: https://projects.blender.org/blender/blender/pulls/116869

[Draise14]

Will only update mention of missing datablocks.

[Draise14]

Mentioned the strip states briefly for visual queues.