API: Add highlight columns

[JinHai-CN]

What problem does this PR solve?

SQL:
SELECT col1, col2 HIGHLIGH col1 FROM tbl1 SEARCH MATCH TEXT ('col1', 'off', 'topn=4');

Python API:
table_object.output(["*"]).highlight('body').match_text('body', question, 2).to_df()

HTTP API:

{
     "output":
     [
         "*"
     ],
     "highlight":
     [
         "col1"
     ]
}

Issue link:#1861

Type of change

• New Feature (non-breaking change which adds functionality)