UI for selecting and re-ordering columns on the table page (#2662)

New Web Component on table/view page with a dialog for selecting and re-ordering columns.

Closes #2661
Refs #1298

tests/test_table_html.py

@@ -730,6 +730,69 @@ async def test_table_html_filter_form_still_shows_nocol_columns(ds_client):
     ]
 
 
+@pytest.mark.asyncio
+async def test_column_chooser_present(ds_client):
+    response = await ds_client.get("/fixtures/facetable")
+    assert response.status_code == 200
+    soup = Soup(response.text, "html.parser")
+    # Web component should be present
+    chooser = soup.find("column-chooser")
+    assert chooser is not None
+    # Script block should contain column data as JSON
+
+    scripts = soup.find_all("script")
+    chooser_script = [s for s in scripts if "_columnChooserData" in (s.string or "")]
+    assert len(chooser_script) == 1
+    script_text = chooser_script[0].string
+    # Extract the JSON data
+    assert "allColumns" in script_text
+    assert "selectedColumns" in script_text
+    assert "primaryKeys" in script_text
+
+
+@pytest.mark.asyncio
+async def test_column_chooser_data_reflects_col_filtering(ds_client):
+    response = await ds_client.get("/fixtures/facetable?_col=state&_col=created")
+    assert response.status_code == 200
+    import json
+    import re
+
+    soup = Soup(response.text, "html.parser")
+    chooser = soup.find("column-chooser")
+    assert chooser is not None
+    scripts = soup.find_all("script")
+    chooser_script = [s for s in scripts if "_columnChooserData" in (s.string or "")]
+    script_text = chooser_script[0].string
+    # Parse the JSON object from the script
+    match = re.search(
+        r"window\._columnChooserData\s*=\s*({.*?});", script_text, re.DOTALL
+    )
+    data = json.loads(match.group(1))
+    # All non-PK columns should still be listed in allColumns
+    assert "state" in data["allColumns"]
+    assert "created" in data["allColumns"]
+    assert "planet_int" in data["allColumns"]
+    # Only state and created should be in selectedColumns (plus pk)
+    non_pk_selected = [
+        c for c in data["selectedColumns"] if c not in data["primaryKeys"]
+    ]
+    assert "state" in non_pk_selected
+    assert "created" in non_pk_selected
+    assert "planet_int" not in non_pk_selected
+
+
+@pytest.mark.asyncio
+async def test_column_chooser_shown_for_views(ds_client):
+    response = await ds_client.get("/fixtures/simple_view")
+    assert response.status_code == 200
+    soup = Soup(response.text, "html.parser")
+    chooser = soup.find("column-chooser")
+    assert chooser is not None
+    scripts = soup.find_all("script")
+    chooser_script = [s for s in scripts if "_columnChooserData" in (s.string or "")]
+    assert len(chooser_script) == 1
+
+
 @pytest.mark.asyncio
 async def test_compound_primary_key_with_foreign_key_references(ds_client):
     # e.g. a many-to-many table with a compound primary key on the two columns