class WireServer

Creates a new RealmBuilder. The client end of `realm_server_end` can be

used to mutate the realm that is being constructed, by doing things such

as adding new children to the realm or adding capability routes between

them. The client end of `builder_server_end` is used to finalize the

realm, after which point it can be launched in a collection.

`pkg_dir_handle` is a handle to the test package. The realm builder

client typically passes a handle to its own `/pkg` directory, and

bundles the `other-component` into the same package.

Identical to `Create`, but instead of the realm being empty by default

it contains the contents of the manifest located in the test package at

the path indicated by `relative_url`, which must be a fragment-only URL

(for example, `#meta/other-component.cm`; see

https://fuchsia.dev/fuchsia-src/reference/components/url#relative-fragment-only).

|bind_handler| returns a handler that binds incoming connections to this

server implementation.

The returned handler borrows the server instance.

The server must outlive the provided |dispatcher|. Only after

the dispatcher is shutdown will it be safe to destroy the servers.

The server should not be moved.