fonts: Add color emoji support for FreeType (#32278)

Color emoji support with "Noto Color Emoji" requires two things:

1. Support for bitmap fonts in the FreeType backend. This requires
   specially handling bitmap fonts which have different characteristics
   in the FreeType API (such as requiring metrics scaling). This support
   is generally ported from Gecko's implementation.
2. When a character is an emoji it "Noto Color Emoji" needs to be in the
   fallback list. Ensure that this is high on the list -- this will be
   improved in a later PR.

Cargo.toml

@@ -116,6 +116,7 @@ tokio-rustls = "0.24"
 tungstenite = "0.20"
 uluru = "3.0"
 unicode-bidi = "0.3.15"
+unicode-properties = { version = "0.1.1", features = ["emoji"] }
 unicode-script = "0.5"
 unicode-segmentation = "1.1.0"
 url = "2.5"

components/gfx/Cargo.toml

@@ -41,6 +41,7 @@ surfman = { workspace = true }
 style = { workspace = true }
 ucd = "0.1.1"
 unicode-bidi = { workspace = true, features = ["with_serde"] }
+unicode-properties = { workspace = true }
 unicode-script = { workspace = true }
 webrender_api = { workspace = true }
 xi-unicode = { workspace = true }