TMP Texts' "Parse Escape Characters" property is disabled manually to replicate legacy Text behaviour

• Updated Unity version to 2021.3.41f1 (simplified codebase accordingly)
• Fixed upgraded Assembly Definition Files losing their Version Defines
• Fixed inline "out Text text" declarations in scripts not being upgraded automatically
• Fixed deprecated function usages in auto-generated extension functions while using TextMesh Pro 3.2 or newer
• Fixed upgrade TMP_InputFields' TextArea.RectMask2D.Padding values sometimes having incorrect values
• Fixed "Upgrading InputField.OnSubmit event using " message being logged even if no OnSubmit event is being upgraded

Fixed compiler warnings and errors on Unity 6 and newest versions of TMP

Fixed exception while upgrading TextMesh objects

• Fixed UnityEvent listeners getting lost during upgrade process on latest Unity versions if the scripts weren't upgraded
• Fixed InputField.OnSubmit event not being upgraded, with a caveat (see https://github.com/yasirkula/UnityTextToTextMeshProUpgradeTool#known-limitations) (closed #2)

Fixed nested/base prefabs sometimes getting upgraded in the wrong order, resulting in prefab override data loss (@rlzicar)

Fixed compiler errors on 2021.2+

Fixed upgraded TMP_InputFields' Viewport -> RectMask2D -> Padding values sometimes being incorrect

• Prefab instance modifications to the upgraded components are now restored
• Components removed as override in prefab instances will remain removed after they are upgraded in the prefab assets
• Fixed references to upgraded components not being updated correctly for some variables after the upgrade
• Fixed TextMesh Pro's assembly being added to custom Assembly Definition Files' referenced assemblies list more than once
• Fixed NullReferenceException when upgrading a Text with unassigned Font
• When InputField is upgraded, children of its newly created viewport (Text Area) have their anchors modified if needed
• Added save/load settings options to the editor window's context menu