tree-sitter : make optional and WASM stubs fix

[stayhydated]

Description

Make tree-sitter optional and fixed WASM stubs like (from cargo check -p gpui-component --target wasm32-unknown-unknown)

error[E0609]: no field `editor_gutter_background` on type `wasm_stub::HighlightThemeStyle`
    --> crates/ui/src/input/element.rs:2135:18
     |
2135 |                 .editor_gutter_background
     |                  ^^^^^^^^^^^^^^^^^^^^^^^^ unknown field
     |
help: a field with a similar name exists
     |
2135 -                 .editor_gutter_background
2135 +                 .editor_background
     |

For more information about this error, try `rustc --explain E0609`.
error: could not compile `gpui-component` (lib) due to 1 previous error

How to Test

cargo check -p gpui-component --no-default-features
cargo check -p gpui-component --features tree-sitter-languages
cargo check -p gpui-component --target wasm32-unknown-unknown
cargo check -p gpui-component --target wasm32-unknown-unknown --features tree-sitter-languages
cargo check --workspace
cargo test -p gpui-component --no-default-features
cargo test -p gpui-component --features tree-sitter-languages

Checklist

• I have read the CONTRIBUTING document and followed the guidelines.
• Reviewed the changes in this PR and confirmed AI generated code (If any) is accurate.
• Passed cargo run for story tests related to the changes.
• Tested macOS, Windows and Linux platforms performance (if the change is platform-specific)