go.*,text,widget{,/material}: enable configurable line wrapping within words

This commit enables consumers of the text shaper to select a policy for how
line breaking candidates will be chosen. The new default policy can break lines
within "words" (UAX#14 segments) when words do not fit by themselves on a line.
This ensures that text does not horizontally overflow its bounding box unless
the available width is insufficient to display a single UAX#29 grapheme cluster.

Fixes: https://todo.sr.ht/~eliasnaur/gio/467
Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

widget/editor.go

@@ -57,6 +57,8 @@ type Editor struct {
 	// Filter is the list of characters allowed in the Editor. If Filter is empty,
 	// all characters are allowed.
 	Filter string
+	// WrapPolicy configures how displayed text will be broken into lines.
+	WrapPolicy text.WrapPolicy
 
 	buffer *editBuffer
 	// scratch is a byte buffer that is reused to efficiently read portions of text
@@ -504,6 +506,7 @@ func (e *Editor) initBuffer() {
 	e.text.Alignment = e.Alignment
 	e.text.SingleLine = e.SingleLine
 	e.text.Mask = e.Mask
+	e.text.WrapPolicy = e.WrapPolicy
 }
 
 // Layout lays out the editor using the provided textMaterial as the paint material