[Serve] add blocking to serve.run()

[GeneDer]

Why are these changes needed?

Rename the existing serve.run to serve._run and added blocking option to the new serve.run

Related issue number

Closes #43211

Checks

• I've signed off every commit(by using the -s flag, i.e., git commit -s) in this PR.
• I've run scripts/format.sh to lint the changes in this PR.
• I've included any doc changes needed for https://docs.ray.io/en/master/.
  • I've added any new APIs to the API Reference. For example, if I added a
    method in Tune, I've added it in doc/source/tune/api/ under the
    corresponding .rst file.
• I've made sure the tests are passing. Note that there might be a few flaky tests, see the recent failures at https://flakey-tests.ray.io/
• Testing Strategy
  • Unit tests
  • Release tests
  • This PR is not tested :(

Manually tested and seeing it behaves correctly

from ray import serve

@serve.deployment
def foo() -> str:
    return "bar"

handle = serve.run(foo.bind(), blocking=True)
xxx = "xxx"

[GeneDer]

Also ensured the blocking option is in the doc https://anyscale-ray--43227.com.readthedocs.build/en/43227/serve/api/doc/ray.serve.run.html#ray.serve.run

[edoakes]

Nice! Please also unify the CLI to call into the same flag

[GeneDer]

@edoakes do you think as is is good enough or if we also want to add blocking to client.deploy_apps as well?

[edoakes]

lgtm that's an internal API anyways