Registering multiple Mach port names with the bootstrap server at
runtime is not how macOS expects it to be used — the bootstrap server
is meant for static services, and the only reason we used it originally
was so child processes could reach back to the UI process.
Remove bootstrap_transport_over_socket(), which had both sides register
dynamic names with the bootstrap server and exchange them over a socket.
Instead, WebDriver and BrowserProcess connections now go through
MachPortServer instances directly. When a non-child process contacts a
MachPortServer, the server creates a port pair on demand (detected via
sysctl ppid check) and returns the local half immediately. This keeps
bootstrap server usage limited to the one original case: child processes
looking up their parent's MachPortServer.
WebDriver Session now runs its own MachPortServer per session.
--webdriver-content-path becomes --webdriver-mach-server-name on macOS.
Spare WebContent launches are skipped when a WebDriver session is active
to avoid bootstrap races.
MultiServer was inherited from SerenityOS where it was used in many
places. Now that BrowserProcess is its only consumer, inline the
connection acceptance logic directly into BrowserProcess and remove
the abstraction.
Instead of wrapping all non-movable members of TransportSocket in OwnPtr
to keep it movable, make TransportSocket itself non-movable and wrap it
in OwnPtr.
