Fix loading raw data from .ttc files on macos (#38753)

# Objective

Ensure that functionality which uses the raw font data (such as
rendering text to canvas) works correctly on macOS when the specified
font is a system font that lives in an OpenType Collection (`.ttc`)
file.

## Changes made

- The `read_data_from_file` in each backend now returns a `index: u32`
in addition to `data: Vec<u8>`
- The `data` field on the `Font` type has been renamed to `raw` and the
`data` method on the `Font` type has been renamed to `raw_font`. This
allows the index to be cached as computing is moderately expensive on
macOS (on the order of 100 microseconds).
- Both of the above now store/return a `struct RawFont` instead of a
`FontData` where `RawFont` is defined as `struct RawFont { data:
FontData, index: u32 }`.
- The users of the `data` method have been updated to use the cached
index from `data` rather than calling `.index()` each time.

---------

Signed-off-by: Nico Burns <nico@nicoburns.com>

components/shared/fonts/Cargo.toml

@@ -12,6 +12,7 @@ name = "fonts_traits"
 path = "lib.rs"
 
 [dependencies]
+ipc-channel = { workspace = true }
 malloc_size_of = { workspace = true }
 malloc_size_of_derive = { workspace = true }
 range = { path = "../../range" }