## Objective
- `bevy_text/src/pipeline.rs` had some crufty code.
## Solution
Remove the cruft.
- `&mut self` argument was unused by
`TextPipeline::create_text_measure`, so we replace it with a constructor
`TextMeasureInfo::from_text`.
- We also pass a `&Text` to `from_text` since there is no reason to
split the struct before passing it as argument.
- from_text also checks beforehand that every Font exist in the
Assets<Font>. This allows rust to skip the drop code on the Vecs we
create in the method, since there is no early exit.
- We also remove the scaled_fonts field on `TextMeasureInfo`. This
avoids an additional allocation. We can re-use the font on `fonts`
instead in `compute_size`. Building a `ScaledFont` seems fairly cheap,
when looking at the ab_glyph internals.
- We also implement ToSectionText on TextMeasureSection, this let us
skip creating a whole new Vec each time we call compute_size.
- This let us remove compute_size_from_section_text, since its only
purpose was to not have to allocate the Vec we just made redundant.
- Make some immutabe `Vec<T>` into `Box<[T]>` and `String` into
`Box<str>`
- `{min,max}_width_content_size` fields of `TextMeasureInfo` have name
`width` in them, yet the contain information on both width and height.
- `TextMeasureInfo::linebreak_behaviour` -> `linebreak_behavior`
## Migration Guide
- The `ResMut<TextPipeline>` argument to `measure_text_system` doesn't
exist anymore. If you were calling this system manually, you should
remove the argument.
- The `{min,max}_width_content_size` fields of `TextMeasureInfo` are
renamed to `min` and `max` respectively
- Other changes to `TextMeasureInfo` may also break your code if you
were manually building it. Please consider using the new
`TextMeasureInfo::from_text` to build one instead.
- `TextPipeline::create_text_measure` has been removed in favor of
`TextMeasureInfo::from_text`
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