fix: put back the convenience API consumers call

[marevol]

The fork kept the widest constructor of several response types and dropped every
overload that delegates to it, plus two empty() factories. All of them are
public entry points in OpenSearch, and consumers call them.

fess hit this the moment main first compiled against the fork. A test that
builds a SearchResponse by hand needs four of them, and without them it has to
read like this:

new ShardSearchFailure(new IllegalStateException(reason), null)
new SearchHits(new SearchHit[0], new TotalHits(0, TotalHits.Relation.EQUAL_TO), 0)
new InternalSearchResponse(hits, null, null, null, timedOut, null, 1,
        Collections.emptyList(), Collections.emptyList())

— a caller that has no phaseTook, no point-in-time id and no search extensions
having to pass all of them and know what the right null is for each. Keeping only
the widest constructor saves nothing: the overloads are one delegating call each.

Restored

type	members
SearchHits	empty(), empty(boolean)
ShardSearchFailure	ShardSearchFailure(Exception)
InternalSearchResponse	empty(), empty(boolean), the 7- and 8-argument constructors
SearchResponse	the 8- and 9-argument constructors

Each body is upstream's, unchanged. None adds state or behaviour; every one
delegates to a constructor that was already here.

Ordering

This needs to be published before codelibs/fess#3442 can go green. fess
main does not compile without it — that PR is otherwise only an import rename
and a dead-override removal.

Verification

• mvn clean install -DskipTests — BUILD SUCCESS.
• mvn test — 636 tests, 0 failures, OpenSearch 3/2/1 and Elasticsearch 8/7 containers included.
• mvn test — see below.
• With this installed, fess main plus fix: make main compile against the forked OpenSearch package fess#3442 reaches
  mvn test-compile BUILD SUCCESS; without it, it does not.