### Title
Update macOS Development Documentation with Dispatch.h Error Solution
### Description
This PR updates the macOS development documentation to include a
solution for the `dispatch/dispatch.h` file not found error. This error
is encountered during local development when using the `cargo run`
command. The documentation now includes steps to ensure the Xcode
command line tools are properly installed and set, and instructions to
set the `BINDGEN_EXTRA_CLANG_ARGS` environment variable.
### Changes
- Added troubleshooting section for `dispatch/dispatch.h` error in
`development/macos.md`.
### Related Issues
- Closes [#11963](https://github.com/zed-industries/zed/issues/11963)
### Testing Instructions
1. Follow the steps in the updated `development/macos.md` to configure
your environment.
2. Run `cargo clean` and `cargo run` to ensure the build completes
successfully.
Release Notes:
- N/A
This PR removes the references to initializing Git submodules as part of
building Zed.
These are no longer needed, as our only submodule was removed in #11672.
Release Notes:
- N/A
