Text Auto Size for UI Toolkit - Best Fit Text

Adds auto-size (best fit) to UI Toolkit Text Elements. It uses manipulators to add the functionality in a non-destructive way so you can add/remove it easily on any TextElement. Tested in Unity 2022 and Unity 6.3. Adds an auto-size option for text elements in the UI Builder (can also be added via USS classes). Support margins and padding. Either you use the UI Builder interface to enable the auto size or you add the text-auto-size USS class to your text elements to enable auto sizing. You can set the min/max size with text-auto-size-min-{SIZE}.