Support for overlaps json operator

Suggestion

The connector support the "contains" json/array operator. This operator select rows which contain ALL value in the array.
I propose the support the "overlaps" json/array operator. This operator select rown which contain ANY value in the array.

Use Cases

With this feature, you will be able to use the JSON Array [array operator &&] operator from PostgreSQL(https://www.postgresql.org/docs/current/functions-array.html).

Examples

Row 1: [ A, B]
Row 2: [C, D]
Row 3: [E, A, B ]
Look for any row which overlaps with [C, F] => Should return Row 2

Acceptance criteria

• Doc
• Test
• Code

It is very easy to implement. Unfortunately, I don't know how to use correctly GitHub for PR. So, I can provide code, and i hope someone will be able to PR it.

/test/postgresql.test.js line 294 -------------

 it('should support the "overlaps" where filter for array type field', async () => {
    await Post.create({
      title: 'Overlaps: LoopBack Participates in Hacktoberfest',
      categories: ['OL_LoopBack', 'OL_Announcements'],
    });
    await Post.create({
      title: 'Overlaps: Growing LoopBack Community',
      categories: ['OL_LoopBack', 'OL_Community'],
    });

    const found = await Post.find({where: {and: [
      {
        categories: {'overlaps': ['OL_Super', 'OL_Community']},
      },
    ]}});
    found.map(p => p.title).should.deepEqual(['Overlaps: Growing LoopBack Community']);
  });

/lib/postgresql.js, line 553 ------------------------------------------------------

case 'overlaps':
  return new ParameterizedSQL(columnName + ' && array[' + operatorValue.map(() => '?') + ']::'
    + propertyDefinition.postgresql.dataType,
  operatorValue);
case 'contains':
  return new ParameterizedSQL(columnName + ' @> array[' + operatorValue.map(() => '?') + ']::'
    + propertyDefin

README.md line 601---------------------------------------------------

Operator overlaps
The overlaps operator allow you to query array properties and pick only
rows where the stored value contains any of the items specified by the query.
The operator is implemented using PostgreSQL array operator &&.
Note The fields you are querying must be setup to use the postgresql array data type - see Defining models above.

lib/postgresql.js の 553 行目付近にある既存の配列演算子処理と、test/postgresql.test.js の関連するケースから始めます。issue の例を使って filter する場合の重複に対するカバレッジを追加し、その後 README.md の 601 行目付近にある演算子のドキュメントを更新します。テストがパスし、PostgreSQL の配列の重複動作がドキュメント化されていれば完了です。