Query tags field with a match query (use mapping analyzer)

The "tags" field is stored in Elasticsearch analysed (by our custom
"uni_normalizer" analyzer). This means, broadly, that in the inverted
index, individual terms in a tag will be stripped of punctuation and
case-normalised.  As such, we need to do the same normalisation when
querying, and the easiest way to do this is with a match query.

This commit changes "tag" queries so that:

- all tag parameters must match
- multiple tokens within one tag query are all required to match

By way of example, for an annotation with tags:

    ["hello", "#THERE", "big world"]

These queries will match:

    tag=hello
    tag=HELLO
    tag=#hello
    tag=hello&tag=there
    tag=hello&tag=there&tag=big+world
    tag=hello&tag=there&tag=world+big

Whereas these will not:

    tag=he+llo
    tag=hello&tag=monkeys
    tag=hello&tag=world

Fixes #2655.

h/api/search/query.py

@@ -197,4 +197,6 @@ def __call__(self, params):
            del params['tags']
        except KeyError:
            pass
        return {'terms': {'tags': [tag for tag in tags]}} if tags else None
        matchers = [{'match': {'tags': {'query': t, 'operator': 'and'}}}
                    for t in tags]
        return {'bool': {'must': matchers}} if matchers else None

h/api/search/test/query_test.py

@@ -402,7 +402,10 @@ def test_tagsmatcher_aliases_tag_to_tags():

    result = query.TagsMatcher()(params)

    assert result == {'terms': {'tags': ['foo', 'bar']}}
    assert result == {'bool': {'must': [
        {'match': {'tags': {'query': 'foo', 'operator': 'and'}}},
        {'match': {'tags': {'query': 'bar', 'operator': 'and'}}},
    ]}}


def test_tagsmatcher_with_both_tag_and_tags():
@@ -411,7 +414,10 @@ def test_tagsmatcher_with_both_tag_and_tags():

    result = query.TagsMatcher()(params)

    assert result == {'terms': {'tags': ['foo', 'bar']}}
    assert result == {'bool': {'must': [
        {'match': {'tags': {'query': 'foo', 'operator': 'and'}}},
        {'match': {'tags': {'query': 'bar', 'operator': 'and'}}},
    ]}}


@pytest.fixture