layout: Clean up inline layout data structures (servo#33149)

- Rename `InlineFormattingContextState` to
  `InlineFormattingContextLayout`.
- Have `InlineFormattingContextLayout` hold a reference to the
 `InlineFormattingContext`, so that it does not need to be passed
 around as an argument
- Have `LineItemLayout` hold a reference to
  `InlineFormattingContextLayout` to avoid duplicating so much data.
- Rename some members of `LineItemLayout` to make it clearer what
  they do.
- Give beter names to many lifetimes and combine some that are
  effectively the same.

Signed-off-by: Martin Robinson <[email protected]>
Co-authored-by: Rakhi Sharma <[email protected]>