Improve `objc2-core-text`

[madsmtm]

The predecessor to objc2-core-text, core-text, has some wrappers that make it easier to use.

It would be nice if we got objc2-core-text to a place where it got good enough to replace that, at least in terms of what font-kit needs.

An (probably a bit incomplete) list of think the list of what core-text provides, that we don't:

• Safe CTFramesetterSuggestFrameSizeWithConstraints wrapper.
• Various CTRun wrappers (these return ).
• CTLineGetTypographicBounds wrapper.
• CTFrameGetLines wrapper that is correctly typed.
• CTFrameGetLineOrigins wrapper.
• Various creation method wrappers for CTFont.
• Safe CTFontGetBoundingRectsForGlyphs wrapper.
• Safe CTFontDrawGlyphs wrapper.
• Various wrappers on CTFont to extract attributes and names.
• Various wrappers on CTFontDescriptor to extract attributes.
• A wrapper over font traits.
• Various creation method wrappers for CTFontCollection.
• Various Send + Sync impls (though I'm not certain that the existing ones are sound?)