VSE: Sound pitch correction

Add sound pitch correction functionality, so that retimed sound strips
can preserve their original pitch.

This has been implemented as a GSoC 2025 project. Actual pitch
correction is done with Rubberband library, which has been already
included into Blender 5.0 library builds; and then most of the other
code has been in Audaspace, which was already updated within Blender
tree earlier.

So this PR just flips on Rubberband build option, and adds the
checkbox to VSE sound strips for pitch correction (on by default for
newly created sound strips). Pitch correction works with both
simple whole-strip retiming, as well as more complex retiming setups
where different parts of the strip use different speeds.

Co-authored-by: Aras Pranckevicius <aras@nesnausk.org>
Pull Request: https://projects.blender.org/blender/blender/pulls/143347

CMakeLists.txt

@@ -420,7 +420,7 @@ mark_as_advanced(WITH_SYSTEM_AUDASPACE)
 if(WITH_AUDASPACE AND NOT WITH_SYSTEM_AUDASPACE)
   option(WITH_RUBBERBAND "\
   Build with Rubber Band for audio time-stretching and pitch-scaling (used by Audaspace)" 
-    OFF
+    ON
   )
 endif()