Fixed Look Dev breaking when docked and rendered at zero size. (#4331)

* Fixed an issue where sometime a docked lookdev could be rendered at zero size and break.

* Update changelog

# Conflicts:
#	com.unity.render-pipelines.high-definition/CHANGELOG.md

Co-authored-by: sebastienlagarde <[email protected]>

Author: JulienIgnace-Unity

com.unity.render-pipelines.core/Editor/LookDev/DisplayWindow.uss

@@ -17,6 +17,7 @@
 
 #viewContainer
 {
+    min-width: 50px;
     flex-shrink: 0;
 }
 

com.unity.render-pipelines.high-definition/CHANGELOG.md

@@ -163,6 +163,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 - Fixed artifact appearing when diffuse and specular normal differ too much for eye shader with area lights
 - Fixed LightCluster debug view for ray tracing.
 - Fixed issue with RAS build fail when LOD was missing a renderer
+- Fixed an issue where sometime a docked lookdev could be rendered at zero size and break.
 
 ### Changed
 - Changed Window/Render Pipeline/HD Render Pipeline Wizard to Window/Rendering/HDRP Wizard