feat: added missing endpoints

[maximilianwerk]

This PR allows easy drop-in replacement for the SimpleIndexer. Changes needed in the wikipedia-example:

# flows/flow.yml

-    uses: 'jinahub://SimpleIndexer'                   # We use the SimpleIndexer for this purpose
+    uses: 'jinahub+docker://FaissPostgresSearcher

# app.py Add roughly the following code

def all_in_one(num_docs, top_k):
    flow = Flow().load_config('flows/flow.yml')
    data_path = os.path.join(
        os.path.dirname(__file__), os.environ.get('JINA_DATA_FILE', None)
    )
    with flow:
        flow.post(
            on='/index', inputs=input_generator(num_docs, data_path), show_progress=True
        )
        flow.post(on='/dump', parameters={'dump_path': 'my_dump.dump', 'shards': 1})
        flow.post(on='/reload', parameters={'dump_path': 'my_dump.dump'})
        while True:
            text = input('Please type a sentence: ')
            doc = Document(content=text)
            result = flow.post(
                on='/search',
                inputs=DocumentArray([doc]),
                parameters={'top_k': top_k},
                line_format='text',
                return_results=True,
            )
            print_topk(result[0], text)

The all_in_one is a combination of /index and /query combined into one Flow. The additional lines are actually only flow.post(on='/dump'...) and flow.post(on='/reload'...). They will be combined into one in the future.

[nan-wang]

This is no longer necessary.