Tag balancing for text widgets

[mark-k]

Based on inspecting the code it looks like tag balancing is not applied to th content of the text widget.

IMO people are more likely to produce broken HTML when adding HTML in a text widget then when writing post, but tag balancing is done only for posts and comments (in which HTML is rarely used).

adds tag balancing to text widget

The patch only changes the way the code is displayed on the front. It does not alter the html input. There may need to be a similar js implementation.

@MikeHansenMe, isn't it better to hook balanceTags to get the use_balanceTags option into play in case there are people that don't want balancing?

uses balanceTags instead of force_balance_tags to make use optional

@mark-k I was thinking mostly of people copying code snippets without knowledge of the code. Perhaps we would be doing them a favor but in the end I think you are right. It should be optional.

Patch still applies

In 35103:

Widgets: add a default filter for widget_text (used by the Text widget), balanceTags, which respects the option for use_balanceTags.

Props MikeHansenMe.
Fixes #23083.