Log Message:
svt-av1: update to 1.7.0.

## [1.7.0] - 2023-08-23

Encoder
- Improve the tradeoffs for the random access mode across presets MR-M13:
 - Quality improvements across all presets and metrics ranging from 0.3% to 4.5% \ 
in BD-rate (!2129)
 - Spacing between presets [M1-M6] has been adjusted to account for the tradeoff \ 
improvements achieved
  - As a user guidance when comparing v1.7 vs v1.6 in a convexhull encoding setup:
   - v1.7.0 M2 is now at similar quality levels as v1.6.0 M1 while being ~50% faster
   - v1.7.0 M3 is now at similar quality levels as v1.6.0 M2 while being ~50% faster
   - v1.7.0 M4 is now at similar quality levels as v1.6.0 M3 while being ~40% faster
   - v1.7.0 M5 is now at similar quality levels as v1.6.0 M4 while being ~30% faster
   - v1.7.0 M6 is now at similar quality levels as v1.6.0 M5 while being ~25% faster
- Added an experimental tune SSIM mode yielding ~3-4% additional SSIM BD-rate \ 
gains (!2109)

Build, cleanup and bug fixes
- Various cleanups and functional bug fixes
- Fix build conflict with libaom

## [1.6.0] - 2023-06-18

Encoder
- Improve the tradeoffs for the random access mode across presets M1-M13:
 - Speeding up the higher quality presets by 30-40%
 - Improving the BD-rate by 1-2% for the faster presets
- Improve the tradeoffs for the low delay mode for both scrren content and \ 
non-screen content encoding modes
- Add a toggle to remove the legacy one-frame buffer at the input of the \ 
pipeline alowing the low delay mode to operate at sub-frame processing latencies
- Add a new API allowing the user to specify quantization offsets for a region \ 
of interest per frame

Build, cleanup and bug fixes
- Various cleanups and functional bug fixes
- Fix the startup minigop size BD-rate loss
- Add ability to run the ci-testing offline