Generalize bbox handling in UI views (DOM and canvas)

[mattpap]

Previously different UI views handled this in their own ways. Now bbox is handled at DOMView level. This in turn allows to simplify View.serializable_state(). In combination with using View.children(), it allows to remove almost all custom implementations (similar to changes in PR #13801). Having a common bbox also allows to uniformy handle positioning of DOM elements associated with renderers. Previously only axes were positioned on a trial basis. In this PR all renderers with a valid bbox are positioned. I also removed some redundant calls to update_geometry() and compute_geometry(), which were revealed by other changes in this PR. Most file changes in this PR are trivial updates to *.blf files.

Example of legend's associated DOM element:

[bryevdv]

Minimal code changes look good, for my curiousity, what kinds of situations could cause these bboxes to be different from each other?

  GlyphRenderer bbox=[45, 11, 334, 119]
    Scatter bbox=[45, 11, 334, 119]

[mattpap]

(...) what kinds of situations could cause these bboxes to be different from each other?

None, GlyphRenderer reports its primary glyph's bbox. However, for the time being I don't include secondary glyphs here, which after PR #13554 allow to have unrelated coordinates and thus bbox from the primary glyph. I could probably skip reporting bbox for glyph renderer, but that would require extra logic.