Decouple theme_importer from old GPUI 1 crates (#3866)

This PR decouples the `theme_importer` from the `theme` and `gpui`
crates.

We achieve this by inlining all of the relevant bits needed to
deserialize Zed1 themes.

This will allow us to continue to import Zed1 themes after we land
#3862.

Release Notes:

- N/A

crates/theme_importer/Cargo.toml

@@ -9,16 +9,15 @@ any_ascii = "0.3.2"
 anyhow.workspace = true
 clap = { version = "4.4", features = ["derive"] }
 convert_case = "0.6.0"
-gpui = { package = "gpui2", path = "../gpui2", features = ["allow-multiple-gpui-versions"] }
-gpui1 = { package = "gpui", path = "../gpui" }
+gpui = { package = "gpui2", path = "../gpui2" }
 indexmap = { version = "1.6.2", features = ["serde"] }
 json_comments = "0.2.2"
 log.workspace = true
 palette = { version = "0.7.3", default-features = false, features = ["std"] }
+pathfinder_color = "0.5"
 rust-embed.workspace = true
 serde.workspace = true
 simplelog = "0.9"
 strum = { version = "0.25.0", features = ["derive"] }
 theme = { package = "theme2", path = "../theme2", features = ["importing-themes"] }
-theme1 = { package = "theme", path = "../theme" }
 uuid.workspace = true