Release notes for 438

Add CollisionGroup property to RaycastParams. This allows you to set a collision group for outgoing raycasts.

xpcall's second argument is now verified to be a function __tostring has to return a string now for tostring() to work

Using non-string hash keys in Luau is now noticeably faster than it used to be.

_VERSION is now set to "Luau"

Please check the backend design doc for developer facing questions

Whenever applicable, Translation/LocalizedStringIds.h has been changed to include a comment for the localization team in order not to translate special characters and things enclosed within parentheses.

Microprofiler dump edge case improvements and bugfixes. Tooltip averages are now more accurate in some edge cases.