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/text.go

@@ -53,6 +53,8 @@ type textView struct {
 	// Truncator is the text that will be shown at the end of the final
 	// line if MaxLines is exceeded. Defaults to "…" if empty.
 	Truncator string
+	// WrapPolicy configures how displayed text will be broken into lines.
+	WrapPolicy text.WrapPolicy
 	// Mask replaces the visual display of each rune in the contents with the given rune.
 	// Newline characters are not masked. When non-zero, the unmasked contents
 	// are accessed by Len, Text, and SetText.
@@ -267,6 +269,10 @@ func (e *textView) Update(gtx layout.Context, lt *text.Shaper, font font.Font, s
 		e.params.MaxLines = e.MaxLines
 		e.invalidate()
 	}
+	if e.WrapPolicy != e.params.WrapPolicy {
+		e.params.WrapPolicy = e.WrapPolicy
+		e.invalidate()
+	}
 
 	e.makeValid()
 	if eventHandling != nil {