Add a TagField desktop control for entering tags

Add a new desktop control, TagField, for entering tags. The user types text and commits it (Return, comma, or paste), and the committed text becomes a rounded, closeable chip ("tag"). Tags wrap onto multiple lines by default, can carry an application data object (like ListBox items), and support:

• Text property round-tripping as comma-joined tags.
• Case-insensitive duplicate rejection (AllowDuplicates) and a MaximumTags limit.
• A TagParsing(text) As Boolean event for custom validation (e.g. email-style checks), with rejected text left in the editor.
• A static suggestion list plus a SuggestionNeeded(prefix) As String() event for dynamic autocomplete, offered below the editor with keyboard navigation.
• TagAdded, TagRemoved, TagPressed, and a unified Changed event, matching ComboBox's event philosophy.
• Read-only display mode, optional close widgets on chips, theme-aware chip colours.

Derived from the forum request "Tags" and Garry's Xojo control XUITagCanvas.