Release notes for 508

The Luau cast operator :: now permits upcasts. 55 :: number | string.

Optimize for RBX::utf8_encode and RBX::utf8_decode prevent copies for passing wchar_t*/char* or R-values for non-windows uses.

Luau: return type of tonumber is corrected to 'number?' instead of 'number'

This ticket fixes various crashes that happen when a script is deleted while being used.

Fixes an issue with script editor where typing in the find search bar would automatically find next.

Hide "Report" option for assets created by current user or Roblox within Toolbox