Misleading namings in `bevy_text`

[ickshonpe]

Problem

The names of some of the components in bevy_text are confusing and inconsistent:

• TextLayoutInfo
  Contains the final computed text layout. The -Info suffix is redundant and potentially confusing.

• TextLayout
  Holds the settings for text justification and line breaking. Not the layout.

• ComputedTextBlock
  This holds the cosmic-text buffer. The name suggests that it contains the final result of a text relayout, but the buffer can be out-of-date until it is updated during the text schedule.

Suggestions

Renamings:

• TextLayoutInfo -> ComputedTextLayout
• ComputedTextBlock -> TextBuffer

Remove the TextLayout component.

JustifyText and LineBreak become components Required by Text and Text2d.